Anthraquinone Dye NIR Luminescence for Security Document Authentication
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for verifying security documents using NIR luminescent features are recognizable to counterfeiters, as these features can be chemically identified and their function guessed based on physical properties, making them easier to falsify.
Innovation Solution
A method involving anthraquinone dyes that luminesce in the NIR spectral range, where the dyes are excited below 650 nm and emit luminescence detectable between 650 nm and 1600 nm, with a significant proportion below 1400 nm, making it difficult for counterfeiters to distinguish the machine-readability of the feature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If luminescent substances are used for security features, then machine-readability and verification capability are improved, but the features become recognizable to counterfeiters who can chemically identify and guess their function
Solution Approach 1:
The patent changes the excitation wavelength parameter to be in the visible range (400-650 nm) rather than UV range, and utilizes the specific luminescence property of anthraquinone dyes that emit in the NIR range (650-1600 nm) with significant proportion below 1400 nm. This parameter change makes the feature recognizable only through specific NIR detection, not general visual inspection, thus reducing counterfeiter recognition while maintaining verification capability
Solution Approach 2:
The patent uses composite ink formulations containing anthraquinone dyes combined with other coloring substances and luminescent properties. The security feature comprises multiple components working together: the anthraquinone dye provides NIR luminescence, while other colorants provide visual appearance. This composite approach requires counterfeiters to replicate multiple properties simultaneously, increasing the difficulty of falsification
2Reliability
If anthraquinone dyes are used for NIR luminescence, then security against forgery is improved, but the complexity of detecting and measuring the luminescence properties increases
Solution Approach 1:
The patent replaces complex cooled detectors with simpler silicon-based detectors that can operate in the NIR range (650-1600 nm) when excited by visible light (400-650 nm). The luminescence emission in the NIR range can be detected using standard silicon photodetectors, eliminating the need for expensive and complex cooled detectors, thus reducing detection complexity while maintaining security
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 security by requiring matching both visual and NIR luminescence properties of the anthraquinone dyes, increasing the difficulty of simulating the substances and thus providing increased protection against forgery and falsification.
Implementation Method 1
at least one marker is selected from the class of anthraquinone dyes... The marker is excited to luminescence, and the luminescence of the at least one marker produced by the excitation is detected in the NIR spectral range
Implementation Method 2
The at least one marker is excited below 650 nm... The marker is excited to luminescence
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The invention relates to a method for verifying a security document or document of value (12) by means of at least one security feature (14) formed by at least one tracer luminescent in the NIR spectral range and selected from the class of anthraquinone dyes.