US 11,749,899 B2
Multilayer structures comprising reflective core layers
Debasish Banerjee, Ann Arbor, MI (US); Songtao Wu, Ann Arbor, MI (US); Naohide Uchida, Shizuoka (JP); Takeshi Yamakawa, Shizuoka (JP); and Hidetaka Asano, Aichi-ken (JP)
Assigned to Toyota Motor Engineering & Manufacturing North America, Inc., Plano, TX (US); and Toyota Jidosha Kabushiki Kaisha, Toyota (JP)
Filed by Toyota Motor Engineering & Manufacturing North America, Inc., Plano, TX (US); and Toyota Jidosha Kabushiki Kaisha, Aichi-ken (JP)
Filed on Mar. 31, 2021, as Appl. No. 17/218,993.
Application 17/218,993 is a continuation of application No. 16/878,723, filed on May 20, 2020, granted, now 10,998,639.
Application 16/878,723 is a continuation of application No. 16/264,096, filed on Jan. 31, 2019, granted, now 10,998,638.
Prior Publication US 2021/0218148 A1, Jul. 15, 2021
Int. Cl. H01Q 17/00 (2006.01); H01Q 15/14 (2006.01); C09D 5/32 (2006.01); C22C 19/05 (2006.01); C09D 5/33 (2006.01)
CPC H01Q 17/002 (2013.01) [C09D 5/004 (2013.01); C09D 5/32 (2013.01); C22C 19/058 (2013.01); H01Q 15/142 (2013.01); H01Q 15/145 (2013.01); Y10T 428/12014 (2015.01); Y10T 428/24917 (2015.01)] 20 Claims
OG exemplary drawing
 
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:

OG Complex Work Unit Math
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); μ0 is permeability; and μr is relative permeability of the metallic material.