Paired Optically Variable Security Element Spectral Matching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing optically variable security elements fail to maintain color matching at a determined angle of incidence across different illumination sources due to different spectral characteristics, leading to inconsistent authentication under various lighting conditions.
Innovation Solution
A paired optically variable security element featuring first and second optically variable interference devices with the same interference design, such as quarter-wave or half-wave designs, where the refractive indices of their dielectric layers differ, ensuring spectral matching at a specific angle of incidence, independent of illumination conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If different quarter-wave or half-wave designs are used to achieve color matching at a determined angle of incidence, then the perceived colors match under specific lighting conditions, but the color matching becomes inconsistent under different illumination sources due to different spectral characteristics
Solution Approach 1:
The patent changes the spectral parameters of the optically variable pigments by using different optical path lengths (quarter-wave vs half-wave designs) to achieve true spectral matching. This ensures that the pigments have identical reflection spectra at the determined angle of incidence, making color authentication independent of illumination source characteristics.
Solution Approach 2:
The patent applies different interference designs (quarter-wave or half-wave) to different regions (first and second optically variable devices) on the same document. Each region has locally optimized spectral characteristics that match at a specific angle of incidence, creating a spatially dependent color authentication feature.
2Reliability
If the same optically variable security element is used in multiple parts of a security document, then counterfeit resistance is enhanced, but the complexity of ensuring consistent spectral characteristics across different parts increases
Solution Approach 1:
The patent divides the security document into multiple parts (first and second optically variable devices) that can be positioned at different locations on the document. Each segment uses the same or complementary optically variable pigments with matching spectral characteristics, allowing distributed security features while maintaining spectral consistency through controlled pigment design.
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 true spectral matching at a determined angle of incidence, ensuring consistent color authentication regardless of the illumination source, enhancing the counterfeit resistance and ease of visual verification of security documents.
Implementation Method 1
first and second optically variable interference devices... which exhibit spectral matching at a determined angle of incidence
Implementation Method 2
the reflection intensity as a function of wavelength... spectral reflection characteristics
Data Source
Figure 1
Figure 2a~2d
Figure 3a~3c
AI summary
Disclosed is a paired optically variable security element which comprises first and second optically variable thin-film multilayer interference devices in the form of optically variable foils or of printings made with inks comprising optically variable interference pigments, wherein said first and second interference devices exhibit spectral matching at a determined angle of incidence. Sets of optically variable devices and of coating compositions comprising optically variable pigments for the production of said paired optically variable security element are also disclosed, as well as the use of said security element for the protection of documents and goods, and security documents and goods carrying same.