Layered element made of transparent layers providing directional diffuse reflection

Patent metadata

Field	Value
Publication number	US-10831092-B2
Application number	US-201816482320-A
Country	US
Kind code	B2
Filing date	Jan 29, 2018
Priority date	Jan 31, 2017
Publication date	Nov 10, 2020
Grant date	Nov 10, 2020

Abstract

A transparent layered element includes two transparent external layers having substantially the same refractive index and each having a smooth external main surface, and a central layer intermediate between the external layers, the central layer including at least one transparent layer of refractive index different from that of the external layers or a metal layer. All the contact surfaces between two adjacent layers of the layered element, one of the two layers of which is a metal layer, or that are two transparent layers of different refractive indices, being textured and parallel to one another, the diffuse light reflection of the layered element on the side of at least one of the external layers having at least one maximum in a direction different from the direction of specular reflection. In addition, the surface of the layered element is divided into a plurality of pixels of same size.

First claim

The invention claimed is:

1. A transparent layered element comprising:
two transparent external layers having substantially the same refractive index and each having a smooth external main surface, and
a central layer intermediate between the external layers, the central layer including at least one transparent layer of refractive index different from that of the external layers or a metal layer,
all the contact surfaces between two adjacent layers of the layered element, one of the two layers of which is a metal layer, or that are two transparent layers of different refractive indices, being textured and parallel to one another,
wherein, for radiation incident on one side of the layered element, the diffuse light reflection of the layered element has at least one maximum in a direction different from the direction of specular reflection,
and wherein a surface of the layered element is divided into a plurality of pixels of same size, each pixel having at least one side of length smaller than or equal to 500 μm, the texture of each textured contact surface within each pixel having a slope distribution f pix having a correlation coefficient r with the slope distribution f tot of the texture of the total textured contact surface, the layered element being such that, for a sample of N pixels, the average of the correlation coefficients r of each pixel of the sample is higher than or equal to 0.8.

2. The transparent layered element as claimed in claim 1 , wherein the layered element is intended to be used, by an observer, lying substantially parallel to a plane Oxy of a coordinate system (O, x, y, z) in which the axis Ox is in a horizontal direction and the axis Oy is in a vertical direction with respect to the observer,
the texture of each of said textured contact surfaces between two adjacent layers of the layered element, one of the two layers of which is a metal layer, or that are two transparent layers of different refractive indices, being of equation z=f(x, y) and having, at each point of coordinates (X 0 , Y 0 ) of the contact surface, a first directional slope θ x and a second directional slope θ y such that:

θ
x

⁡

(

X
0

,

Y
0

)

=

arctan
⁢

dz
dx

⁢

|

X
0

,

Y
0

⁢

⁢
and

θ
y

⁡

(

X
0

,

Y
0

)

=

arctan
⁢

dz
dy

⁢

|

X
0

,

Y
0

,

the slope distribution of the texture of each of said textured contact surfaces, which corresponds to the frequency of each pair of slopes (θ x , θ y ), not having axial symmetry about at least one of the axes (Oθ x , Oθ y ) of a first orthogonal coordinate system (O, θ x , θ y ) where O corresponds to the pair of slopes (0, 0), or not having axial symmetry about at least one of the axes (Oθ x ′, Oθ y ′) of a second orthogonal coordinate system (O, θ x ′, θ y ′) obtained by rotating by 45° the first orthogonal coordinate system (O, θ x , θ y ).

3. The transparent layered element as claimed in claim 2 , wherein the slope distribution of the texture of each of said textured contact surfaces, which corresponds to the frequency of each pair of slopes (θ x , θ y ), does not have axial symmetry about at least one of the axes of an orthogonal coordinate system centered on O.

4. The transparent layered element as claimed in claim 2 , wherein the slope distribution of the texture of each of said textured contact surfaces, which corresponds to the frequency of each pair of slopes (θ x , θ y ), has, excluding a potential peak centered on O, a single peak not centered on O.

5. The transparent layered element as claimed in claim 2 , wherein the slope distribution of the texture of each of said textured contact surfaces, which corresponds to the frequency of each pair of slopes (θ x , θ y ), has, excluding a potential peak centered on O, at least two peaks not centered on O.

6. The transparent layered element as claimed in claim 5 , wherein all the peaks of the slope distribution of the texture of each of said textured contact surfaces are aligned along a single axis of an orthogonal coordinate system centered on O.

7. The transparent layered element as claimed in claim 5 , wherein the slope distribution of the texture of each of said textured contact surfaces, which corresponds to the frequency of each pair of slopes (θ x , θ y ), has two peaks that are symmetric to each other with respect to one of the axes of an orthogonal coordinate system centered on O.

8. The transparent layered element as claimed in claim 2 , wherein the slope distribution of the texture of each of said textured contact surfaces, which corresponds to the frequency of each pair of slopes (θ x , θ y ), has, excluding a potential peak centered on O, at least one peak not centered on O and for which the aspect ratio, which is a ratio between the width of the peak along the axis Oθ x and the width of the peak along the axis Oθ y , is different from 1.

9. The transparent layered element as claimed in claim 1 , wherein an average of the correlation coefficients r (f pix , f tot ) of each pixel of the sample is higher than or equal to 0.9.

10. The transparent layered element as claimed in claim 1 , wherein each pixel has at least one side of length smaller than or equal to 150 μm.

11. The transparent layered element as claimed in claim 10 , wherein the length is smaller than or equal to 100 μm.

12. The transparent layered element as claimed in claim 1 , wherein the sample of N pixels is

Assignees

• Saint Gobain

Inventors

• Schiavoni Michele
• Ozanam Cécile
• Gayout Patrick

Classifications

• G03B21/62 Primary

  Translucent screens · CPC title

• G02B5/0221

  the surface having an irregular structure (G02B5/0226 takes precedence) · CPC title

• B32B2605/006

  Transparent parts other than made from inorganic glass, e.g. polycarbonate glazings · CPC title

• B32B2307/418

  Refractive · CPC title

• B32B2307/412

  Transparent · CPC title