Chromatic effect light reflective unit

Patent metadata

Field	Value
Publication number	US-2023152498-A1
Application number	US-202117916714-A
Country	US
Kind code	A1
Filing date	Apr 16, 2021
Priority date	Apr 16, 2020
Publication date	May 18, 2023
Grant date	—

Abstract

The present invention is directed to a chromatic effect light reflective unit (1; 1a-1g). The unit (1; 1a-1g) comprises a reflective layer (10) having at least one reflective surface (11), and a chromatic diffusion layer (20) having a first surface (21) proximal to the reflective surface (11) and a second surface (23), opposite and substantially parallel to the first, configured to be illuminated by incident light, wherein the chromatic diffusion layer (20) comprises a nano-pillar (70) or nano-pore (30) 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 (n1), in which the first and second materials are substantially non-absorbing or transparent to electromagnetic radiations with wavelength included in the visible spectrum, wherein the ratio (nM/nm) between a higher refractive index (nM) and a lower refractive index (nM) chosen between the first (n1) and the second (n2) refractive indexes is comprised between 1.05 and 3, wherein the nano- pillars (71) or nano-pores (31) have a development along a main direction not parallel to the first surface (21) and the second surface (23) of the chromatic diffusion layer and the nano- pillars (70) or nano-pores (30) structure is characterized by a plurality of geometric parameters comprising a pillar diameter or pore diameter (dp), a pillar length or pore length (1p) along said main development direction, and a surface density of nano-pillars or nano-pores (Dp) and/or a structure (30,70) porosity (Pp) and wherein the pillar diameter or pore diameter (dp) is comprised between 40 nm and 300 nm, the length (lp) along the main development direction is comprised between 300 nm and 40 µm (300 nm < lp < 40 µm) and at least one between the surface density of nano-pillars or nano-pores (Dp) and the structure (30,70) porosity (Pp) is configured to provide a higher regular reflectance for wavelengths of incident light comprised in the range of red with respect to wavelengths of incident light comprised in the range of blue and a higher diffuse reflectance for wavelengths of incident light comprised in the range of blue than wavelengths of incident light comprised in the range of red.

First claim

1 . Chromatic effect light reflective unit ( 1 ; 1 a - 1 g ) comprising
a reflective layer ( 10 ) having at least one reflective surface ( 11 ), and a chromatic diffusion layer ( 20 ) having a first surface ( 21 ) proximal to the reflective surface ( 11 ) and a second surface ( 23 ), opposite and substantially parallel to the first, configured to be illuminated by incident light, wherein the chromatic diffusion layer ( 20 ) comprises a nano-pillar ( 70 ) or nano-pore ( 30 ) structure in a first material having a first refractive index ( n 1 ), immersed in a second material having a second refractive index ( n 2 ) other than the first ( n 1 ), in which the first and second materials are substantially non-absorbing or transparent to electromagnetic radiations with wavelength included in the visible spectrum, wherein the ratio (n M /n m ) between a higher refractive index (n M ) and a lower refractive index (n m ) chosen between the first ( n 1 ) and the second ( n 2 ) refractive indexes is comprised between 1.05 and 3, wherein the nano-pillars ( 71 ) or nano-pores ( 31 ) have a development along a main direction not parallel to the first surface ( 21 ) and the second surface ( 23 ) of the chromatic diffusion layer and the nano-pillars ( 70 ) or nano-pores ( 30 ) structure is characterized by a plurality of geometric parameters comprising: a pillar diameter or pore diameter (d p ), a pillar length or pore length (l p ) along said main development direction, and a surface density of nano-pillars or nano-pores (D p ) and a structure ( 30 , 70 ) porosity (P p ), and wherein the pillar diameter or pore diameter (d p ) is comprised between 40 nm and 300 nm, the length (l p ) along the main development direction is comprised between 0.3 µm and 40 µm (0.3 µm < l p < 40 µm) and at least one between the surface density of nano-pillars or nano-pores (D p ) and the structure ( 30 , 70 ) porosity (P p ) is configured to provide a higher regular reflectance for wavelengths of incident light comprised in the range of red with respect to wavelengths of incident light comprised in the range of blue and a higher diffuse reflectance for wavelengths of incident light comprised in the range of blue than wavelengths of incident light comprised in the range of red.

2 . Unit ( 1 ; 1 a - 1 g ) according to claim 1 ,
in which the development along the main direction of the nano-pillars ( 71 ) or nano-pores ( 31 ) is characterized by a directional order parameter comprised between 0.7 and 1, more preferably between 0.9 and 1, calculated as: S = 2 < cos 2 ϑ > − 1 , wherein ϑ is the angle comprised between the main development direction identified in a section plane transversal to the first surface ( 21 ) and the second surface ( 23 ) of the chromatic diffusion layer ( 20 ), and an axis associable with each nano-pillar or nano-pore of a plurality of nano-pillars or nano-pores lying in the section plane; and/or wherein the nano-pillars ( 71 ) or the nano-pores ( 31 ) have a distribution with respect to the second surface ( 23 ) of the chromatic diffusion layer ( 20 ) divided into coherence areas extending less than 100 µm 2 , preferably less than 10 µm 2 , more preferably less than 1 µm 2 , wherein each nano-pillar ( 71 ) or nano-pore ( 31 ) within one of said coherence area of the second surface ( 23 ) is substantially equidistant from adjacent nano-pillars ( 71 ) or adjacent nano-pores ( 31 ), present in the same coherence area.

3 . Unit ( 1 ; 1 a - 1 g ) according to claim 1 or 2 , wherein the diameter (d p ) is comprised between 70 nm and 200 nm, preferably comprised between 80 nm and 160 nm.

4 . Unit ( 1 ; 1 a - 1 g ) according to any one of claims 1 to 3 , wherein the length along the main direction of the nano-pillars ( 71 ) or nano-pores ( 31 ) is comprised between 500 nm and 20 µm (500 nm < l p < 20 µm), preferably comprised between 500 nm and 20 µm (500 nm < l p < 20 µm).

5 . Unit ( 1 ; 1 a - 1 g ) according to any one of the preceding claims , wherein the surface density (D p ) is such as to define an inter-pore or inter-pillar distance (Ip) less than 2.8 times the diameter (d p ), preferably less than 2.6 times the diameter (d p ), more preferably less than 2.4 times the diameter (d p ).

6 . Unit ( 1 ; 1 a - 1 g ) according to any one of the preceding claims , wherein the porosity (P p ) of the structure ( 30 , 70 ) is comprised between 20% and 80%, preferably between 25% and 75%.

7 . Unit ( 1 ; 1 a - 1 g ) according to any one of the preceding claims , wherein the diameter (d p ) is greater than a second diameter threshold value (d p_threshold _2) and/or the length (l p ) is greater than a second length threshold value (l p_threshold_2 ) such as to provide a dichroic reflectance ratio (r = R(λ r , θ)/ R(λ b , θ)) of the electromagnetic radiation reflectances at the wavelengths of λ b = 450 nm and λ r = 630 nm of a luminous flux reflected by the unit (1; 1a ― 1g) by regular reflection, increasing as the angle of incidence of a corresponding luminous flux incident on the unit ( 1 ; 1 a - 1 g ) increases and exhibiting a variation of the dichroic reflectance value (r) higher than 5%, preferably higher than 10%, more preferably 15% of the dichroic reflectance value (r) of a luminous flux reflected by the unit ( 1 ; 1 a - 1 g ) by regular reflection in the case of a luminous flux incident on the unit ( 1 ; 1 a - 1 g ) at an angle of incidence of about 10°.

8 . Unit ( 1 ; 1 a - 1 g ) according to claim 7 , wherein
when the ratio (n M /n m ) between the higher refractive index (n M ) and the lower refractive index (n m ) is comprised between 1.7 and 1.9, the second diameter threshold value (d p_threshold_2 ) is comprised between 40 nm and 100 nm, preferably between 60 nm and 80 nm, even more preferably it is equal to about 70 nm; and/or when the ratio (n M /n m ) between the higher refractive index (n M ) and the lower refractive index (n m ) is comprised between 1.7 and 1.9, the second length threshold value (l p_threshold_2 ) is comprised between 300 nm and 2 µm, preferably between 1 µm and 1.7 µm, more preferably it is equal to about 1.4 µm; and/or when the ratio (n M /n m ) between the higher refractive index (n M ) and the lower refractive index (n m ) is comprised between 1.1 and 1.3, the diameter threshold value (d p _ threshold ) is comprised between 150 nm and 190 nm, more preferably between 160 nm and 180 nm, even more preferably it is equal to about 170 nm.; and/or when the ratio (n M/ n m ) between the higher refractive index (n M ) and the lower refractive index (n m ) is comprised between 1.1 and 1.3, the second length threshold value (l p_threshold_2 ) is comprised between 4 µm and 8 µm, preferably between 5 µm and 7 µm, even more preferably it is equal to about 6 µm.

9 . Unit ( 1 ; 1 a - 1 g ) according to any one of the preceding claims , wherein the diameter (d p ) is greater than a diameter threshold value (d p _ threshold ) and/or the length (l p ) is greater than a length threshold value (lp_ threshold ) such as to provide a variability in the correlated colour temperature of a luminous flux reflected by the unit ( 1 ; 1 a - 1 g ) by regular reflection, as a function of an angle of incidence of a corresponding luminous flux incident on the unit ( 1 ; 1 a - 1 g ) with wavelength comprised between 380 nm and 740 nm, and wherein
the correlated colour temperature of a luminous flux reflected by the unit ( 1 ; 1 a - 1 g ) by regular reflection decreases as the angle of incidence increases; and
a maximum Euclidean distance (Δ R max (u′,v′)) between pairs of colour points of a regularly reflected beam t

Assignees

• Coelux Srl

Inventors

• Bonanomi Simone
• Usseglio Nanot Sandro
• Brazzo Paolo
• Fossati Vittorio

Classifications

• G02B5/26

  Reflecting filters (G02B5/28 takes precedence) · CPC title

• C09D5/36

  Pearl essence, e.g. coatings containing platelet-like pigments for pearl lustre · CPC title

• F21V7/22

  characterised by materials, surface treatments or coatings, e.g. dichroic reflectors · CPC title

• C04B2237/343

  Alumina or aluminates · CPC title

• F21V14/04

  by movement of reflectors {(in vehicle head lamps F21S41/675)} · CPC title