Security Marking with Spectrally Varying Decay Time
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Solution Overview
Problem
Existing security features for documents of value that use luminescent substances with partially overlapping emissions lack sufficient protection against forgery due to limited combinatorial diversity and complexity in analyzing multi-exponential decay curves, particularly in time-critical situations like banknote processing.
Innovation Solution
A security marking system utilizing a combination of luminescent substances with partially overlapping emission spectra and significantly different decay times, where the overall decay time varies continuously with wavelength, providing a high degree of overlap and variance in decay time behavior to enhance forgery protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If luminescent substances with partially overlapping emissions are used, then analysis complexity increases, but protection against forgery remains insufficient due to limited combinatorial diversity
Solution Approach 1:
The patent changes the parameter of decay time to be spectrally continuously varying across the emission spectrum. By measuring decay time at multiple wavelengths and observing how it changes continuously, the system creates a unique spectral fingerprint that is extremely difficult to replicate, thereby enhancing forgery protection while maintaining manageable analysis complexity through systematic wavelength scanning.
Solution Approach 2:
The patent uses combinations of multiple luminescent substances with different decay characteristics to create composite luminescent materials. These composites exhibit complex, spectrally varying decay behavior that is difficult to analyze and even more difficult to replicate, providing enhanced security while the systematic measurement approach keeps analysis complexity controlled.
2Reliability
If luminescent substances with significantly different decay times are combined, then combinatorial diversity increases, but analysis of multi-exponential decay curves becomes technically complex and time-consuming
Solution Approach 1:
The patent measures decay time at multiple discrete wavelengths across the emission spectrum, which is more than a single measurement but less than continuous spectral analysis. This partial action approach provides sufficient information to detect spectral variations in decay time while keeping the measurement process rapid and suitable for high-speed banknote processing, avoiding the time cost of full spectral decomposition.
Solution Approach 2:
Instead of attempting to resolve and analyze multiple exponential decay components at each wavelength, the patent directly measures the effective decay time parameter at multiple wavelengths and looks for spectral variations. This parameter-based approach bypasses the complex mathematical decomposition of multi-exponential decays while still capturing the essential security information.
3Ease of operation
If luminescent substances with identical or slightly different emission wavelengths are used, then evaluation is simplified, but selection of luminescent substances is restricted and identification variability is limited
Solution Approach 1:
The patent adds the spectral dimension to decay time measurement by measuring how decay time varies across different wavelengths. This transforms a single-parameter measurement (decay time at one wavelength) into a multi-parameter measurement (decay time across the spectrum), enabling the use of diverse luminescent substance combinations while maintaining evaluation simplicity through systematic wavelength scanning.
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 allows for reliable, rapid, and simple identification of documents of value, offering increased security against imitation and enabling effective protection in high-speed banknote processing environments.
Implementation Method 1
the security marking is designed in the form of a combination of at least two luminescent substances which have different individual decay times
Implementation Method 2
It has long been known to provide documents of value with luminescent substances that have a specific emission behavior for this purpose
Data Source
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AI summary
The invention relates to a value document having a security marking in the form of two luminescent substances, the emission spectra of which partially overlap in a primary emission range, wherein the emission spectra have a degree of overlap of less than 80% and more than 5%, wherein the luminescent substances have different individual decay times in the primary emission range, wherein the individual decay times of the luminescent substances differ from one another by more than 50%, relative to the shortest individual decay time.