Luminescent Security Features Using Overlapping Spectra and Decay Ratios
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Solution Overview
Problem
Existing security document systems face challenges in enhancing security without increasing complexity or manufacturing costs, particularly in distinguishing between different classes of securities using luminescent substances with overlapping emission spectra.
Innovation Solution
A security document system comprising at least two securities documents, each featuring a combination of luminescent substances with partially overlapping emission spectra and specific decay times, intensity ratios, and decay time sums, utilizing complementary spectral properties of garnet and rare-earth oxysulfide, phosphate, or vanadate materials, to create distinct encodings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple luminescent substances with distinct emission spectra are used to distinguish security document classes, then security and classification capability are improved, but sensor complexity and manufacturing costs increase
Solution Approach 1:
The patent changes the spectral parameters of luminescent substances by using substances with partially overlapping emission spectra instead of completely distinct spectra. This allows multiple security document classes to be distinguished through combinations of luminescent substances and their decay times, while using simpler sensors with fewer spectral channels. The key parameter change is moving from distinct to overlapping emission spectra, enabling reduced sensor complexity while maintaining security.
Solution Approach 2:
The patent employs composite luminescent features combining multiple luminescent substances with overlapping spectra. By creating composite materials where different substances have partially overlapping emission ranges, the system achieves enhanced security through combination coding while the overlapping nature allows simpler sensor detection. The composite approach uses substances like rare-earth oxysulfides, phosphates, and vanadates with controlled spectral overlaps.
2Reliability
If multiple luminescent substances with overlapping emission spectra are used to create distinct codes, then counterfeit protection is improved, but manufacturing complexity increases
Solution Approach 1:
The patent utilizes decay time as an additional parameter to distinguish security document classes. By assigning different decay times to different luminescent substances or combinations, the system creates multiple distinguishable codes using a limited set of luminescent materials. This parameter change from spectral distinctness to temporal characteristics simplifies manufacturing while enhancing counterfeit protection.
Solution Approach 2:
The patent applies different luminescent substance combinations to different regions or features within security documents. By varying the local composition of luminescent materials and their decay characteristics, the system creates region-specific codes that enhance security without requiring complex manufacturing processes. Each region can be independently treated with specific luminescent substances.
3Speed
If luminescent substances with decay times less than 5 ms are used, then detection speed is improved, but the number of distinguishable codes is reduced
Solution Approach 1:
The patent creates composite luminescent features by combining multiple substances with different decay times. Even though individual substances have decay times less than 5 ms, the combinations produce distinct decay time sums and ratios that can be used to differentiate multiple security document classes. This composite approach maintains fast detection while increasing code capacity.
Solution Approach 2:
The patent transitions from using spectral dimensions for code differentiation to using temporal dimensions (decay time characteristics). By measuring decay time sums and ratios across different spectral channels, the system creates multiple distinguishable codes through temporal patterns rather than spectral distinctness. This dimensional shift enables faster detection while maintaining code versatility.
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
This approach enhances security by allowing for numerous, easily distinguishable codes with high counterfeit protection, utilizing simpler sensors and lower spectral resolution, while reducing production complexity and costs.
Implementation Method 1
the first luminescent substance of the security element in the first security document is a luminescent substance of a first class, and the second luminescent substance of the first security document is a luminescent substance of a second class
Implementation Method 2
the emission spectra of the first and second luminescent substances partially overlap
Implementation Method 3
the first and second luminescent substances of the security element in the first security document have a decay time of less than 5 ms
Data Source
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AI summary
The invention relates to a valuable document system, a method for identifying a valuable document of a valuable document system, and a luminescent substance set. The valuable document system comprises at least one first and one second valuable document. The first valuable document has a security feature composed of a combination of at least one first and one second luminescent substance of a first and a second substance class, respectively. The second valuable document has a security feature comprising at least one first luminescent substance of the first or second substance class. By comparison with the security feature of the second valuable document, the security feature of the first valuable document has at least a different intensity ratio of the emission, a different decay time ratio and/or a different decay time sum in two adjacent spectral ranges.