Electroluminescent Security Feature Verification Using UV Irradiation
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Solution Overview
Problem
The existing methods for verifying electroluminescent security features in value and security documents are imprecise due to external influences on the frequency spectrum, leading to difficulties in distinguishing genuine from counterfeit pigments and limited reproducibility, resulting in uncertain authenticity detection.
Innovation Solution
A method and device that utilize a characteristic function to model the system response to electrical excitation, incorporating light radiation in the UV wavelength range during excitation and detection, allowing for improved selectivity by altering the luminescence response and encoding information in the excitation signal, which is then evaluated for verification decisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temporal detection and spectral decomposition of luminescence response is used, then the harmonic component can be evaluated to identify electroluminescent pigment, but measurement precision deteriorates due to external influences changing frequency spectrum components
Solution Approach 1:
The patent changes the excitation parameters by using a controlled electrical excitation signal with specific frequency characteristics instead of conventional excitation methods. This allows the system to excite the electroluminescent pigment in a way that produces a characteristic luminescence response that is less sensitive to external spectral influences, thereby improving both measurement precision and reproducibility
Solution Approach 2:
The patent implements a feedback mechanism where the detected luminescence response is used to adjust and optimize the excitation signal parameters. By continuously monitoring the luminescence output and adjusting the electrical excitation accordingly, the system compensates for external influences on the frequency spectrum, maintaining reliable and reproducible measurements
2Measurement precision
If conventional luminescence detection method is used, then electroluminescent pigment can be identified, but selectivity deteriorates making it difficult to distinguish similar pigments
Solution Approach 1:
The patent adds a temporal dimension to the detection by analyzing the time-resolved luminescence response characteristics. Instead of relying solely on spectral decomposition, the system evaluates the temporal profile of the luminescence decay, which provides an additional dimension of information that enhances the ability to distinguish between similar electroluminescent pigments with different decay characteristics
Solution Approach 2:
The patent employs dynamic excitation and detection methods, using time-varying electrical excitation signals and analyzing the transient luminescence response. This dynamic approach captures the temporal behavior of different pigments, which varies even when spectral properties are similar, thereby improving selectivity in pigment identification
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 the selectivity and reliability of electroluminescent security feature verification by differentiating between similar pigments and improving the signal-to-noise ratio, reducing errors from external factors and non-linearities, and increasing the difficulty of counterfeiting.
Implementation Method 1
printing inks and preparations with electroluminescent pigments are used, which exhibit luminescence in the visible and/or non-visible spectral range when excited in a static or dynamic electric field
Implementation Method 2
the security element also being irradiated at least temporarily with light radiation in the UV wavelength range during the excitation of the security element
Data Source
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AI summary
The invention relates to a method for verifying an electroluminescent security feature (2) in a value and/or security document (3), comprising the following steps: exciting the electroluminescent security feature (2) by means of an electrical excitation signal (8); sensing radiation emitted by the security feature (2) and generating an output signal (11); evaluating the output signal (11) and deriving a verification decision; and outputting the verification decision; wherein additionally the security element (2) is irradiated with light radiation (31) in the UV wavelength range during the excitation of the security element (2) and/or the sensing of the emitted radiation. The invention further relates to a device for verification.