Tri-luminescent Security Ink for Banknotes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing security features in documents such as banknotes are vulnerable to forgery due to ease of counterfeiting, and existing luminescent technologies require complex multilayer systems or suffer from intensity reduction and stability issues.
Innovation Solution
A security ink containing a combination of first and second inorganic fluorescent and phosphorescent pigments that emit distinct emission spectra under different excitation wavelengths and after excitation termination, providing a tri-luminescent effect without the need for multiple layers, enhancing forgery resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple inks with different UV-fluorescent pigments are overprinted to create different emission wavelengths, then the security feature becomes more complex and harder to counterfeit, but the intensity of emission is reduced by the overprinted layers
Solution Approach 1:
The patent combines multiple fluorescent and phosphorescent pigments into a single ink formulation, eliminating the need for multiple overprinted layers. This single-layer approach maintains high emission intensity while providing complex luminescent characteristics that are difficult to counterfeit.
Solution Approach 2:
The invention uses composite pigment formulations containing both fluorescent and phosphorescent materials in a single ink. This composite approach enables multiple emission wavelengths and prolonged luminescence without requiring multiple printing layers, thus avoiding intensity reduction.
2Ease of manufacture
If standard organic UV-fluorescent pigments are used, then the printing process is simpler, but the chemical and physical stability is low
Solution Approach 1:
The patent employs composite formulations combining inorganic fluorescent pigments with phosphorescent additives. The inorganic base provides superior chemical and physical stability, while the phosphorescent components enhance security features. This composite approach maintains ease of printing while dramatically improving stability.
3Adaptability or versatility
If bi-luminescence effects with core-shell pigments are used, then two different emission wavelengths are achieved, but the production complexity increases and the shell absorbs excitation light
Solution Approach 1:
Instead of using complex core-shell structures, the patent merges multiple separate pigment types (fluorescent and phosphorescent) into a single ink formulation. This approach achieves multiple emission wavelengths without the manufacturing complexity of core-shell pigments and without excitation light absorption by shell materials.
4Ease of manufacture
If UV-fluorescent pigments with broad emission peaks are used, then the security feature is easier to produce, but high-resolution verification tools are required
Solution Approach 1:
The patent incorporates phosphorescent pigments with specific emission characteristics that provide localized spectral features. These phosphorescent components emit at distinct wavelengths with characteristic decay times, enabling verification with simpler tools that can detect phosphorescence specifically, reducing the need for high-resolution spectral analysis.
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
The tri-luminescent security ink offers complex and easily recognizable color changes, is chemically and physically stable, and simplifies the printing process, while maintaining high security against counterfeiting.
Implementation Method 1
a first fluorescent and phosphorescent pigment and a second fluorescent pigment, wherein the security ink, (in particular if printed onto a substrate) if excited with a first wavelength emits radiation with a first emission spectrum, if excited with a second wavelength emits radiation with a second emission spectrum being different from the first emission spectrum, and after the excitation has been terminated emits radiation with a third emission spectrum being different from the first emission spectrum and being different from the second emission spectrum
Implementation Method 2
a first fluorescent and phosphorescent pigment and a second fluorescent pigment, wherein the security ink, (in particular if printed onto a substrate) if excited with a first wavelength emits radiation with a first emission spectrum, if excited with a second wavelength emits radiation with a second emission spectrum being different from the first emission spectrum, and after the excitation has been terminated emits radiation with a third emission spectrum being different from the first emission spectrum and being different from the second emission spectrum
Implementation Method 3
a first fluorescent and phosphorescent pigment and a second fluorescent pigment, wherein the security ink, (in particular if printed onto a substrate) if excited with a first wavelength emits radiation with a first emission spectrum, if excited with a second wavelength emits radiation with a second emission spectrum being different from the first emission spectrum
Data Source
AI summary
A security ink contains at least a first fluorescent and phosphorescent pigment and a second fluorescent pigment, wherein the security ink if excited with a first wavelength emits radiation with a first emission spectrum, if excited with a second wavelength emits radiation with a second emission spectrum being different from the first emission spectrum, and after the excitation has been terminated emits radiation with a third emission spectrum being different from the first emission spectrum and being different from the second emission spectrum.