Optical Storage Phosphor Verification via Dynamic Luminescence Sequences

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Solution Overview

Problem

Existing authenticity assessment methods for valuable documents using optical storage phosphors are vulnerable to imitation since they rely on reproducible measurements that do not account for the dynamic behavior of the phosphors, allowing counterfeiters to recreate the substances and pass authenticity tests.

Innovation Solution

The method involves applying sequences of charging and readout processes to optical storage phosphors, detecting the dynamic behavior of the phosphors through readout time series, and evaluating these sequences to determine characteristic memory properties, making the system path-dependent and harder to replicate.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If standard spectroscopy measurement methods are used to detect optical storage phosphors, then the measurement process is simple and reproducible, but the security against imitation is reduced because imitators can easily characterize and recreate the substances

Engineering Contradiction:
Improvemeasurement process simplicityVSAvoidsecurity against imitation
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent transitions from static spectroscopy measurements to dynamic measurement sequences that capture the temporal evolution of luminescence signals. Multiple readout processes are performed at different time points after excitation, creating time-resolved signal patterns that characterize the phosphor's dynamic behavior. This dynamic approach makes counterfeiting difficult because imitators would need to replicate not just the spectral properties but also the temporal dynamics of the luminescence decay.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the measurement parameters from single-point spectroscopy to multi-point temporal measurements. By measuring luminescence intensity at multiple time points (t1, t2, t3, ...) after excitation, the system captures the decay kinetics of the phosphor. This parameter transformation from spatial/spectral domain to temporal domain creates a more complex characterization that is harder to replicate without knowing the specific measurement sequence and evaluation algorithm.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If reproducible measurements at defined states are used, then the measurement results are consistent and reliable, but the ability to differentiate between similar feature substances is reduced

Engineering Contradiction:
Improvemeasurement result consistencyVSAvoiddifferentiation capability
Core Design Contradiction:
Measurement precisionVSDifficulty of detecting and measuring

Solution Approach 1:

The patent employs periodic excitation and readout cycles to probe the phosphor's luminescence properties. By repeatedly exciting the phosphor and measuring the luminescence decay at standardized time intervals, the system creates a reproducible measurement protocol. This periodic measurement approach ensures consistency across different measurements while capturing the characteristic decay pattern that enables differentiation between similar phosphor materials.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent adds a temporal dimension to the measurement by recording luminescence intensity as a function of time after excitation. Instead of relying solely on spectral characteristics, the system measures the time-resolved luminescence decay, creating a new dimension of information. This temporal dimension provides additional discriminatory power for distinguishing between similar phosphor substances while maintaining measurement precision through standardized timing protocols.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Reliability

If dynamic behavior measurement is implemented, then the security against imitation increases due to path-dependency, but the device complexity and measurement time increase

Engineering Contradiction:
Improvesecurity against imitationVSAvoidmeasurement system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements preliminary excitation steps that prepare the phosphor in a known initial state before the actual measurement sequence. By pre-exciting the phosphor and allowing it to reach a standardized starting condition, the system ensures that subsequent dynamic measurements begin from a reproducible state. This preliminary action reduces the need for complex real-time control during measurement while maintaining the path-dependent characteristics that provide security.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent creates a digital copy or fingerprint of the phosphor's dynamic luminescence behavior through the measurement sequence. By recording the temporal decay pattern and storing it as a characteristic signature, the system transforms the complex dynamic measurement into a comparable data representation. This copying approach simplifies the evaluation process while preserving the security benefits of dynamic measurement, as the captured temporal pattern serves as a unique identifier that is difficult to replicate.

Inventive Principle:
Principle #26Copying

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 security by creating a unique, specific connection between the authenticity feature and the verification process, making it difficult for imitators to recreate the dynamic behavior and thus increasing the authenticity assurance of valuable documents.

Implementation Method 1

uses the optically stimulated luminescence (OSL) of optical storage phosphors as an authenticity feature

Methodology Applied
Scientific EffectOptically stimulated luminescence (OSL): Luminescence

Implementation Method 2

Detecting at least one first and one second readout measurement value, each of which is based on the detection of an optical emission in response to the respective first and second associated readout processes

Methodology Applied
Scientific EffectPhosphorescence: Phosphorescence

Data Source

PatentEP3469560B1Method for securing value documents using storage phosphors
Publication Date: 2022.08.10 GIESECKE & DEVRIENT CURRENCY TECHNOLOGY GMBH
  • EP3469560B1 patent drawingFigure 1~2
  • EP3469560B1 patent drawingFigure 3~4
  • EP3469560B1 patent drawingFigure 5~6

AI summary

The invention relates to a method for verifying an authenticity feature comprising a storage phosphor, a verification device, an authenticity feature, and a value document comprising an authenticity feature. The authenticity feature includes a storage phosphor. According to the disclosed method, in one step, the storage phosphor is subjected to at least one query sequence, each of which comprises at least a first reading process and a second reading process. Furthermore, at least a first read measured value and a second read measured value are acquired which are based on the detection of an optical emission in response to the first and the second associated reading process, respectively. In another step, a time series of the read measured values is established, said time series being associated with the at least one query sequence and comprising at least the first read measured value associated with the first reading process and the second read measured value associated with the second reading process. The time series of the read measured values which is associated with the query sequence is analyzed in another step in order to determine a dynamic behavior from said time series of the read measured values under the associated query sequence.