Metameric Security Pigments for Wide-Range Lighting Authentication
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Solution Overview
Problem
Existing security devices fail to achieve a consistent color match under a wide range of lighting conditions using similar or dissimilar pigment designs, leading to ineffective color shifting for authentication purposes.
Innovation Solution
A security device utilizing a first color-shifting pigment with a five-layer structure and a second pigment with a seven-layer structure, where the dielectric materials and optical thicknesses are differently configured to ensure a seamless color match at a first viewing angle and a distinct mismatch at a second viewing angle, regardless of lighting conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If similar pigment designs with dissimilar dielectric materials are used, then color match can be achieved under certain lighting conditions, but the color match fails under a wide range of lighting conditions
Solution Approach 1:
The patent changes the physical structure parameters of the pigment layers (thickness ratios, layer configurations) rather than relying on dielectric material properties. Specifically, it uses a thinner dielectric layer interference pigment combined with a non-shifter interference pigment, where the thickness parameters are optimized to achieve wavelength-independent color matching across varying lighting conditions
Solution Approach 2:
The patent creates a composite pigment system by combining two different types of interference pigments (thinner dielectric layer shifter and thicker dielectric layer non-shifter) in a single security device. This composite approach allows the pigments to work together to achieve consistent color matching under wide lighting conditions, overcoming the limitations of using single pigment types
2Ease of manufacture
If the same pigment design and similar dielectric materials are used, then manufacturing is simplified, but color matching is not achieved or only within a narrow lighting range
Solution Approach 1:
The patent applies different quality characteristics to different pigment layers. The first interference pigment uses a thinner dielectric layer configuration optimized for color shifting, while the second interference pigment uses a thicker dielectric layer configuration optimized for providing a stable reference color. This local differentiation in layer thickness allows each pigment to perform its specific function while maintaining overall manufacturability
3Adaptability or versatility
If low chromaticity pigments are used, then color match over wide lighting conditions is achieved, but the color performance is too low to be effective
Solution Approach 1:
The patent optimizes the chromaticity parameters by selecting pigment materials and layer thicknesses that provide both wide lighting adaptability and high color performance. The thinner dielectric layer interference pigment is designed with specific chromatic properties that maintain vibrancy while achieving broad lighting condition compatibility, unlike conventional low chromaticity pigments
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 enables a vibrant, eye-catching pattern that remains invisible at the first viewing angle and becomes visible upon tilting, providing effective authentication across various lighting conditions.
Implementation Method 1
The spectral results of these two pigments did not match well because the spacing and width of the reflection peaks and valleys in the reflection spectra of these pigments was different
Implementation Method 2
a first color-shifting pigment and a second pigment on a substrate, wherein the first color-shifting pigment and the second pigment color match at a first viewing angle; and wherein the first color-shifting pigment and the second pigment color mismatch as a second viewing angle
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
There is disclosed a security device, including a substrate; a first color-shifting pigment on a first region of the substrate; and a second pigment, including at least three dielectric layers, on a second region of the substrate; wherein the first color-shifting pigment and the second pigment color match at a first viewing angle. Methods of making and using the security device are also disclosed.