Overlapping Luminescence Markers for Value Document Authentication
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Solution Overview
Problem
Existing document authentication systems face challenges in reliably distinguishing between different classes of documents of value due to sensor tolerances and production fluctuations, limiting the number of distinguishable coding classes, especially in high-speed banknote processing.
Innovation Solution
A luminescence feature comprising a first and second luminescence marker with spectrally similar infrared emission spectra and arranged to overlap in the surface area, allowing for differential evaluation to compensate for environmental and sensor variations, and a manufacturing method that includes printing or applying these markers on the document substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional single luminescence marker is used, then manufacturing is simple, but authentication reliability is limited due to sensor tolerances and production fluctuations
Solution Approach 1:
The single luminescence marker is segmented into multiple luminescence markers (first, second, and optionally third markers) with different spectral characteristics. Each marker responds differently to excitation light across the spectral range, creating a unique spectral fingerprint that enhances authentication reliability while compensating for sensor tolerances and production fluctuations.
Solution Approach 2:
The invention changes the spectral parameters of the luminescence markers by selecting materials with different emission spectra. The first marker has a first spectral characteristic, the second marker has a second spectral characteristic, and optionally the third marker has a third spectral characteristic. These parameter variations enable differential evaluation that compensates for environmental and sensor variations.
2Reliability
If multiple luminescence markers with different spectral characteristics are used, then authentication reliability improves, but manufacturing precision requirements increase
Solution Approach 1:
The invention applies partial action by using only the spectral differences that are necessary for authentication. The luminescence markers are positioned at specific locations (first subarea, second subarea, and optionally third subarea) and excited with broadband light, requiring only that their spectral characteristics differ sufficiently for discrimination, not that they meet extremely tight manufacturing tolerances.
Solution Approach 2:
The invention uses optical copying through broadband excitation light that simultaneously excites multiple luminescence markers. The sensor captures the combined luminescence spectrum, and through evaluation algorithms, the system distinguishes between different markers based on their spectral characteristics without requiring precise physical positioning or manufacturing tolerances.
3Productivity
If traditional luminescence features are used, then processing speed can be maintained, but the number of distinguishable coding classes is limited
Solution Approach 1:
The invention adds spectral dimensionality to the luminescence coding system. Instead of relying solely on intensity or position variations, the system uses multiple luminescence markers with different spectral characteristics (emission spectra, peak wavelengths, bandwidths). This spectral dimension enables exponential increase in the number of distinguishable coding classes while maintaining high processing speeds through parallel spectral measurement.
Solution Approach 2:
The invention uses composite luminescence materials with different spectral properties as the basis for multiple coding classes. By combining luminescence markers made from different materials or formulations with distinct spectral characteristics, the system creates a versatile coding platform that can distinguish between many different document classes simultaneously at high processing speeds.
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
Enhances authentication reliability by compensating for sensor and environmental fluctuations, enabling precise distinction between different classes of documents, even at high processing speeds, and providing a high level of protection against counterfeiting.
Implementation Method 1
a first luminescence marker in a first subarea and a second luminescence marker in a second, different subarea. The first and second luminescence markers are able to be excited to luminesce at the same wavelength, hereinafter sometimes also referred to as excitation wavelength, and luminesce, after excitation, essentially in the same emission band in the infrared spectral range
Data Source
AI summary
A flat document of value has a surface area having a longitudinal direction and a transverse direction and which is provided with a luminescence feature in the surface area. The luminescence feature includes a first luminescence marker in a first subarea and a second luminescence marker in a second, different subarea. The first and second luminescence markers are able to be excited to luminesce at the same wavelength and luminesce, after excitation, essentially in the same emission band in the infrared spectral range. The first and second luminescence markers have spectrally similar infrared emission spectra, namely infrared emission spectra that have a spectral difference between 0.5% and 15%. The first and second subarea are arranged so as to overlap one another in the surface area in projection onto the longitudinal direction and/or in projection onto the transverse direction.