Value Document Luminescence Testing with Rank-Based Measurements
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Solution Overview
Problem
Existing methods for detecting luminescent substances in value documents are unreliable due to variations in luminescence intensity caused by factors like printing, soiling, and substrate properties, making it difficult to determine authenticity and concentration accurately.
Innovation Solution
A method that captures luminescence intensity values at multiple locations on the substrate and determines a substrate luminescence characteristic value based on a rank order of these values, independent of capture location, to provide a measure of luminescent substance concentration that is less affected by printing or soiling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If luminescence intensity is measured at a single location or averaged over all locations, then the measurement process is simple, but the result is unreliable due to variations caused by printing, soiling, and substrate properties
Solution Approach 1:
The substrate surface is divided into multiple discrete measurement locations, and luminescence intensity is measured at each location separately. This segmentation allows identification of locations with typical substrate properties, excluding regions affected by printing, soiling, or other disturbances. The final characteristic value is derived from a subset of these segmented measurements, improving reliability while maintaining manageable complexity.
Solution Approach 2:
Different measurement locations on the substrate are treated differently based on their local quality. Locations with typical substrate properties (free from printing, soiling, or defects) are selected for inclusion in the characteristic value calculation, while locations with atypical properties are excluded. This local quality assessment ensures that the luminescence characteristic value reflects only the substrate's inherent properties.
2Measurement precision
If luminescence intensity is averaged over all locations including printed or soiled regions, then the measurement covers the entire substrate, but the result is distorted by regions that weaken luminescence radiation
Solution Approach 1:
Measurement locations with atypical properties (printed regions, soiled areas, defects) are extracted and excluded from the calculation of the luminescence characteristic value. Only measurements from locations with typical substrate properties are used. This extraction ensures that the characteristic value accurately reflects the substrate's luminescence properties without being distorted by external factors.
Solution Approach 2:
The presence of printed or soiled regions, which normally distort measurements, is converted into a benefit by using them as reference points to identify and exclude problematic areas. The variation in luminescence intensity caused by these regions provides information about which locations to exclude, thereby improving the accuracy of the final characteristic value.
3Reliability
If the luminescence characteristic value depends on the position and orientation of the substrate, then the measurement is easy to perform, but the result varies significantly with substrate placement
Solution Approach 1:
The substrate is divided into multiple measurement locations, and the luminescence characteristic value is derived from a subset of these locations that exhibit typical substrate properties. This segmentation approach makes the measurement independent of the substrate's overall position and orientation, as long as at least some typical locations are included in the measurement set.
Solution Approach 2:
The evaluation method changes from using a single absolute luminescence intensity value to using a characteristic value derived from multiple measurements and statistical evaluation. This parameter transformation makes the result invariant to position and orientation changes, improving reliability without complicating operation.
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 accurate determination of luminescent substance concentration in value documents, independent of position and orientation, enabling reliable authenticity and quality checks even in the presence of printing or soiling.
Implementation Method 1
Upon illumination with suitable optical excitation radiation, such a luminescent substance emits luminescent radiation having luminescent properties characteristic of the luminescent substance
Implementation Method 2
a luminescence sensor for capturing a luminescence intensity for the specified luminescent substance and forming a corresponding luminescence intensity value
Data Source
AI summary
A method is provided for checking a substrate with a specified luminescent substance incorporated and/or applied areally. A substrate luminescent characteristic value for the substrate is ascertained, for which purpose a number N of luminescence intensity values are captured at respectively different locations on the value document, and the substrate luminescence characteristic value is ascertained in dependence on a rank order of the luminescence intensity values. It can be checked whether the substrate luminescence characteristic value meets a specified criterion.