Omnidirectional high chroma red structural colors

• US 9,810,824 B2
• Filed: 05/02/2016
• Issued: 11/07/2017
• Est. Priority Date: 01/28/2015
• Status: Active Grant

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Motor Engineering & Manufacturing North America Incorporated (Toyota Motor Corporation)
• Inventors: Banerjee, Debasish, Zhou, Li Qin
• Primary Examiner(s): CHERRY, EUNCHA P
• Application Number:
  US15/144,283
• Publication Number:
  US 20160245969A1
• Time in Patent Office: 554 Days
• Field of Search: 359584
• CPC Class Codes: G02B 5/0825 the reflecting layers comprising dielectric materials only
• CPC Class Codes: G02B 5/0858 the reflecting layers comprising a single metallic layer with one or more dielectric layers
• CPC Class Codes: G02B 5/26 Reflecting filters G02B5/28 takes precedence
• CPC Class Codes: G02B 5/286 having four or fewer layers, e.g. for achieving a colour effect

Abstract

A multilayer thin film that reflects an omnidirectional high chroma red structural color. The multilayer thin film may include a reflector layer, at least one absorber layer extending across the reflector layer, and an outer dielectric layer extending across the at least one absorber layer. The multilayer thin film reflects a single narrow band of visible light when exposed to white light and the outer dielectric layer has a thickness of less than or equal to 2.0 quarter wave (QW) of a center wavelength of the single narrow band of visible light.

Claims

1. A multilayer interference thin film that reflects an omnidirectional high chroma red structural color comprising:

a multilayer thin film having a reflector layer, at least one absorber layer extending across the reflector layer; and

an outer dielectric layer extending across the at least one absorber layer;

wherein the multilayer thin film reflects a single narrow band of visible light when exposed to white light and the outer dielectric layer has a thickness of less than or equal to 2.0 quarter wave (QW) of a center wavelength of the single narrow band of visible light, the single narrow band of visible light having;

a visible full width half maximum (FWHM) width of less than 200 nm;

a color between 0° and

30°

on a Lab color space; and

a hue shift of less than 30°

on the Lab color space when the multilayer thin film is viewed at angles between 0-45°

relative to a direction normal to an outer surface of the outer dielectric layer.

2. The multilayer interference thin film of claim 1, wherein the reflector layer has a thickness between 5-200 nm and is made from at least one of Al, Ag, Pt and Sn.

3. The multilayer interference thin film of claim 1, wherein the at least one absorber layer is at least one dielectric absorber layer extending between the reflector layer and the outer dielectric layer.

4. The multilayer interference thin film of claim 3, wherein the at least one dielectric absorber layer is made from at least one of an oxide and a nitride.

5. The multilayer interference thin film of claim 4, wherein the at least one dielectric absorber layer is made from at least one of Fe₂O₃ and TiN, and has a thickness between 5-500 nm.

6. The multilayer interference thin film of claim 1, wherein the outer dielectric layer has an index of refraction greater than 1.6.

7. The multilayer interference thin film of claim 6, wherein the outer dielectric layer is made from at least one of MgF₂, ZnS and TiO₂.

8. The multilayer interference thin film of claim 7, wherein the center wavelength of the single narrow band of reflected visible light is between 600-700 nm and the thickness of the outer dielectric layer is less than 175 nm.

9. The multilayer interference thin film of claim 1, wherein the at least one absorber layer is a dielectric absorber layer and a transparent absorber layer.

10. The multilayer thin film of claim 9, wherein the transparent absorber layer extends across the dielectric absorber layer and is located between the dielectric absorber layer and the outer dielectric layer.

11. The multilayer interference thin film of claim 9, wherein the dielectric absorber layer is made from at least one of Fe₂O₃ and TiN.

12. The multilayer interference thin film of claim 10, wherein the dielectric absorber layer has a thickness between 5-500 nm.

13. The multilayer interference thin film of claim 9, wherein the transparent absorber layer is made from at least one of Cr, Ge, Ni, stainless steel, Ti, Si, V, TiN, W, Mo, Nb and Fe₂O₃.

14. The multilayer interference thin film of claim 13, where the transparent absorber layer has a thickness between 5-20 nm.

15. The multilayer interference thin film of claim 1, wherein the single narrow band of visible light has a visible FWHM width of less than 200 nm, a color between 5°

and 25°

on the Lab color space, and a hue shift of less than 20°

on the Lab space color map when the multilayer thin film is viewed at angles between 0-45°

relative to a direction normal to an outer surface of the outer dielectric layer.

16. The multilayer interference thin film of claim 1, wherein the single narrow band of visible light has a visible FWHM width of less than 200 nm, a color between 10°

and 25°

on the Lab color space, and a hue shift of less than 15°

on the Lab space color map when the multilayer thin film is viewed at angles between 0-45°

relative to a direction normal to an outer surface of the outer dielectric layer.

17. An omnidirectional high chroma red structural color multilayer thin film comprising:

a multilayer thin film having a reflector layer, a dielectric absorber layer extending across the reflector layer, an outer dielectric layer extending across the dielectric absorber layer and a transparent absorber layer extending between the dielectric absorber layer and the outer dielectric layer;

wherein the multilayer thin film reflects a single narrow band of visible light when exposed to white light and the outer dielectric layer has a thickness of less than or equal to 2.0 quarter wave (QW) of a center wavelength of the single narrow band of visible light, the single narrow band of visible light having;

a visible full width half maximum (FWHM) FWHM width of less than 200 nm;

a color between 0° and

30°

on a Lab color space; and

a hue shift of less than 30°

on the Lab color space when the multilayer thin film is viewed at angles between 0-45°

relative to a direction normal to an outer surface of the outer dielectric layer.

18. The omnidirectional high chroma red structural color multilayer thin film of claim 17, wherein the dielectric absorber layer is made from at least one of an oxide and a nitride, and has a thickness between 5-500 nm.

19. The omnidirectional high chroma red structural color multilayer thin film of claim 18, wherein the dielectric absorber layer is made from at least one of Fe₂O₃ and TiN.

20. The omnidirectional high chroma red structural color multilayer thin film of claim 17, wherein the transparent absorber layer is made from at least one of Cr, Ge, Ni, stainless steel, Ti, Si, V, TiN, W, Mo, Nb and Fe₂O₃, and has a thickness between 5-20 nm.