Luminescent Security Marking for Fast Banknote Authentication
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Solution Overview
Problem
Existing luminescent materials and evaluation methods for security documents with non-exponential decay behavior have limited combinatorial diversity, leading to restricted marking variability and are unsuitable for high-speed authentication, particularly in time-critical situations like banknote processing.
Innovation Solution
A security marking using at least two luminescent substances with non-monoexponential time behavior, excited by a single pulse, where the mixing ratio is identified through a linear combination of their time-dependent luminescence intensities, allowing for rapid and reliable authentication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If non-linear fitting is used to determine amplitudes and decay times of luminescent materials, then the identification accuracy is improved, but the computation time increases significantly and the method becomes susceptible to noise
Solution Approach 1:
The patent applies preliminary action by pre-characterizing luminescent materials with simple exponential decay models before actual authentication. The system stores reference decay curves and uses these pre-prepared models to rapidly compare against measured samples, eliminating the need for time-consuming non-linear fitting during authentication while maintaining identification accuracy through the preliminary characterization work
Solution Approach 2:
The patent employs a simplified evaluation model that uses basic exponential decay functions instead of complex non-linear fitting algorithms. This approach uses computationally inexpensive, simple mathematical models that provide sufficient accuracy for authentication purposes, trading off some theoretical precision for dramatically reduced computation time and noise susceptibility
2Adaptability or versatility
If luminescent materials with non-exponential decay behavior are used, then the combinatorial diversity is improved, but the suitability for high-speed authentication deteriorates
Solution Approach 1:
The patent applies parameter changes by transforming the complex non-exponential decay behavior into an equivalent representation using simple exponential decay parameters. By fitting or approximating the decay curves with exponential functions characterized by amplitude and decay time parameters, the system maintains the diversity information while enabling rapid evaluation through standard exponential decay analysis suitable for high-speed authentication
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
Enables reliable and fast identification of security marks with improved counterfeit protection, utilizing a wide variety of luminescent substances and reducing computation time by three orders of magnitude compared to non-linear fitting methods.
Implementation Method 1
the at least two luminescent substances are simultaneously excited by an excitation pulse and have different time courses of the intensities of emitted radiation when excited by the excitation pulse
Data Source
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AI summary
The invention relates to a value document having a security marking in the form of at least two luminescent substances, which are present in a defined relative quantity proportion and can be excited together by an excitation pulse. The time curves of the intensities are different and at least one luminescent substance has a non-monoexponential time curve. In a method for identifying the security marking, the time curve of the common intensity is detected and a linear combination of formula (I) is adapted, wherein Ii(t) are time curves of the intensities of the luminescent substances. The security marking is identified based on the linear coefficients Ci.