Omnidirectional Red Structural Color via Segmented Absorber Layers
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Solution Overview
Problem
Current multilayer stack pigments that exhibit high-chroma red color require a large number of thin film layers, making production costly, and face challenges in angular independence and hue control, especially for red colors which have a narrow dark red hue space and high angular variance.
Innovation Solution
A multilayer stack structure comprising a reflective core layer, a metal absorber layer, and a dielectric absorber layer that reflects a single band of visible light with a hue between 0-40° on the a*b* Lab color map, with minimal hue shift when viewed from different angles, using materials like aluminum, copper, and iron oxide, and employing dry or wet deposition techniques to achieve a compact and efficient design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a large number of thin film layers are used to achieve high-chroma red color, then the desired color properties are obtained, but the production cost increases significantly
Solution Approach 1:
The patent segments the absorber function into two distinct layers: a metal absorber layer and a dielectric absorber layer. This segmentation allows each layer to target specific wavelength ranges, with the metal absorber handling certain bands and the dielectric absorber handling others, thereby achieving complete spectrum absorption with fewer total layers compared to using a single material system
Solution Approach 2:
The patent employs composite material structures by combining metal absorber materials (such as chromium, copper, or aluminum) with dielectric absorber materials (such as zinc sulfide or silicon dioxide) in a multilayer configuration. This composite approach leverages the complementary absorption characteristics of metal and dielectric materials to achieve high-chroma red color with reduced layer count
2Manufacturing precision
If thicker dielectric layers are used to achieve red color, then the desired hue is obtained, but angular independence deteriorates due to high harmonic design
Solution Approach 1:
The patent extracts and eliminates the harmonic distortion problem by introducing the dielectric absorber layer specifically positioned to absorb the second and third harmonic wavelengths that would otherwise cause color shifts at oblique viewing angles. This selective extraction of harmful harmonics preserves angular independence while maintaining the thicker dielectric layer needed for red hue
Solution Approach 2:
The patent converts the potentially harmful effect of thicker dielectric layers (which generate harmonics causing angular dependence) into a benefit by strategically placing the dielectric absorber layer to selectively absorb these harmonic wavelengths. The harmonics that would normally degrade angular independence are instead utilized as target wavelengths for the dielectric absorber, transforming a problem into a solution
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides an omnidirectional high-chroma red structural color pigment with minimal layer count, reducing production costs and achieving non-noticeable color shift across angles, effectively addressing the challenges of angular independence and hue control for red colors.
Implementation Method 1
The multilayer stack reflects a single band of visible light with a hue between 0-40° on an a*b* Lab color map... provides a non-noticeable color shift to the human eye
Implementation Method 2
a metal absorber layer extending across the reflective core layer... made from such materials such as colorful metals, e.g. copper (Cu), gold (Au), bronze (Cu—Zn alloys), brass (Cu—Sn alloys)
Implementation Method 3
a dielectric absorber layer extending across the metal absorber layer... made from colorful dielectric materials such as but not limited to iron oxide (Fe2O3)
Data Source
AI summary
A high-chroma omnidirectional red structural color pigment. The omnidirectional structural color pigment is in the form of a multilayer stack that has a reflective core layer, a metal absorber layer extending across the reflective core layer and a dielectric absorber layer extending across the metal absorber layer. The multilayer stack reflects a single band of visible light with a hue between 0-40°, and preferably between 10-30°, on an a*b* Lab color map. The single band of visible light has a hue shift of less than 30° on the a*b* Lab color map when viewed from all angles between 0-45° normal to an outer surface of the multilayer stack.