Multilayer structures comprising reflective core layers

Patent metadata

Field	Value
Publication number	US-11749899-B2
Application number	US-202117218993-A
Country	US
Kind code	B2
Filing date	Mar 31, 2021
Priority date	Jan 31, 2019
Publication date	Sep 5, 2023
Grant date	Sep 5, 2023

Abstract

A multilayer thin film that reflects an omnidirectional structural color having a reflective core layer comprising a metallic material, a second layer extending across the reflective core layer, a third layer extending across the second layer, and an outer layer extending across the third layer. The multilayer thin film reflects a single narrow band of visible light that is less than 30° measured in Lab color space when viewed from angles between 0° and 45°, and the reflective core layer has a skin depth δ of greater than or equal to 1.0 μm in a frequency range from 20-40 GHz, as calculated by:
δ = 2 ⁢ ρ ( 2 ⁢ π ⁢ f ) ⁢ ( μ 0 ⁢ μ r ) ≈ 5 ⁢ 0 ⁢ 3 ⁢ ρ μ r ⁢ f ,
δ is skin depth in meters (m); ρ is resistivity in ohm meter (Ω·m); f is frequency of an electromagnetic radiation in hertz (Hz); μ 0 is permeability; and μ r is relative permeability of the metallic material.

First claim

What is claimed is:

1. A multilayer thin film that reflects an omnidirectional structural color comprising:
a reflective core layer comprising a metallic material;
a second layer extending across the reflective core layer, wherein the second layer is a dielectric absorber or dielectric material;
a third layer extending across the second layer, wherein the third layer comprises a semi-transparent absorbing layer; and
an outer layer extending across the third layer, wherein the outer layer is formed from a dielectric material or a colorful dielectric material, wherein
the multilayer thin film reflects a single narrow band of visible light that is less than 30° measured in Lab color space when the multilayer thin film is exposed to broadband electromagnetic radiation and viewed from angles between 0° and 45° relative to a direction normal to an outer surface of the multilayer thin film, and
the reflective core layer has a skin depth δ of greater than or equal to 1.0 μm in a frequency range from 20-40 GHz, as calculated by:

δ
=

2
⁢
ρ

(

2
⁢
π
⁢
f

)

⁢

(

μ
0

⁢

μ
r

)

≈

5
⁢
0
⁢
3
⁢

ρ

μ
r

⁢
f

,

wherein
δ is skin depth in meters (m); ρ is resistivity in ohm meter (Ω·m); f is frequency of an electromagnetic radiation in hertz (Hz); μ 0 is permeability; and μ r is relative permeability of the metallic material.

2. The multilayer thin film of claim 1 , wherein the metallic material is NiCr.

3. The multilayer thin film of claim 1 , wherein the reflective core layer has a skin depth δ of greater than or equal to 0.5 μm in a frequency range from 40-100 GHz, as calculated by:

δ
=

2
⁢
ρ

(

2
⁢
π
⁢
f

)

⁢

(

μ
0

⁢

μ
r

)

≈

5
⁢
0
⁢
3
⁢

ρ

μ
r

⁢
f

,

wherein
δ is skin depth in m; ρ is resistivity in Ω·m; f is frequency of an electromagnetic radiation in Hz; μ 0 is permeability; and μ 2 is relative permeability of the metallic material.

4. The multilayer thin film of claim 1 , wherein the second layer is formed from Fe 2 O 3 , TiN, ZnS, or combinations thereof.

5. The multilayer thin film of claim 1 , wherein the third layer is formed from W, Cr, Ge, Ni, stainless steel, Pd, Ti, Si, V, TiN, Co, Mo, Nb, ferric oxide, amorphous silicon, or combinations thereof.

6. The multilayer thin film of claim 1 , wherein the outer layer is formed from a dielectric material selected from the group consisting of ZnS, ZrO 2 , CeO 2 , TiO 2 , or combinations thereof.

7. A paint, polymer, or coating comprising the multilayer thin film of claim 1 .

8. A multilayer thin film that reflects an omnidirectional structural color comprising:
a reflective core layer comprising a metallic material;
a protective layer encapsulating the reflective core layer;
a second layer extending across at least a portion of the protective layer;
a third layer extending across the second layer; and
an outer layer extending across the third layer, wherein the outer layer is formed from a dielectric absorbing material or a dielectric material, wherein
the multilayer thin film reflects a single narrow band of visible light having a color shift of the single narrow band of visible light is less than 30° measured in Lab color space when the multilayer thin film is exposed to broadband electromagnetic radiation and viewed from angles between 0° and 45° relative to a direction normal to an outer surface of the multilayer thin film, and
the reflective core layer has a skin depth δ of greater than or equal to 1.0 μm in a frequency range from 20-40 GHz, as calculated by:

δ
=

2
⁢
ρ

(

2
⁢
π
⁢
f

)

⁢

(

Assignees

• Toyota Eng & Mfg North America
• Toyota Motor Co Ltd

Inventors

• Banerjee Debasish
• Wu Songtao
• Uchida Naohide
• Yamakawa Takeshi
• ASANO Hidetaka

Classifications

• H01Q17/002 Primary

  using short elongated elements as dissipative material, e.g. metallic threads or flake-like particles · CPC title

• C09D5/004

  Reflecting paints; Signal paints · CPC title

• C09D5/32

  Radiation-absorbing paints {(protection against X-, gamma- or corpuscular radiation G21F)} · CPC title

• C22C19/058 Primary

  without Mo and W · CPC title

• H01Q15/142

  using insulating material for supporting the reflecting surface · CPC title