Security Element with Dual Metal Layers for Forgery-Proofing
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Solution Overview
Problem
Existing security elements for documents like bank notes and ID cards can be easily imitated, particularly in cursory checks under incident light, as they primarily rely on metallic coatings that can be replicated with aluminum foil, lacking sufficient forgery-proofness.
Innovation Solution
A security element with two metal layers of different optical densities, where the optically denser layer has a lower transmission and appears opaque, while the optically thinner layer is semitransparent, providing distinct visual and machine-readable features that are difficult to imitate, especially when combined with diffraction structures and complex patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single metallic coating is used for security elements, then the manufacturing process is simple and cost-effective, but the forgery-proofness is insufficient as aluminum foil can easily replicate the effect
Solution Approach 1:
The single metallic coating is segmented into multiple metal layers with different optical densities. The optically denser layer (e.g., aluminum) provides the metallic luster, while the optically thinner layer (e.g., gold, silver, copper, or chromium) provides distinctive optical properties that are difficult to replicate. This segmentation transforms a simple replicable structure into a complex multi-layer structure that resists forgery.
Solution Approach 2:
The patent applies composite materials by combining multiple metal layers with different optical densities on a substrate. This composite structure creates complex optical effects including varying transmission, reflection, and absorption characteristics that cannot be easily replicated by simple aluminum foil, thereby enhancing security while maintaining manufacturing feasibility through established vacuum deposition techniques.
2Reliability
If multiple metal layers with different optical densities are applied, then forgery-proofness is enhanced, but the manufacturing precision requirements increase significantly
Solution Approach 1:
The patent controls manufacturing precision by systematically varying key parameters: the optical density of each metal layer is controlled within specific ranges (optically denser layer: 0.05-0.50, optically thinner layer: 0.50-1.50), and layer thicknesses are optimized (denser layer: 20-300 nm, thinner layer: 2-20 nm). These parameter specifications provide clear manufacturing targets that balance security performance with production feasibility using standard vacuum deposition equipment.
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 security element significantly enhances forgery-proofness by creating visually and machine-distinguishable effects under different lighting conditions, making it extremely challenging to replicate, and allows for machine-readable coding, thus ensuring authenticity.
Implementation Method 1
The optically denser metal layer of the at least two metal layers, hereinafter referred to as metal layer A, shows a lower transmission, preferably a maximum transmission of 30%, especially preferred a maximum of 10%
Implementation Method 2
The optically thinner metal layer of the at least two metal layers, hereinafter referred to as metal layer B, shows a higher transmission than layer A, preferably more than 10%, especially preferred 25 to 80%
Implementation Method 3
The substrate can be provided with diffraction structures in the form of a relief structure
Data Source
AI summary
The invention relates to a security element for security papers, bank notes, ID cards or the like, with a substrate, on which are disposed at least two metal layers, the metal layers having different optical densities.