Multi-Layer Security Element for Banknote Authentication
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Solution Overview
Problem
Current security elements in banknotes, such as those using vacuum-deposited metal layers, face challenges in creating varying thicknesses for adjacent opaque and semi-transparent zones, making it difficult to produce complex authentication features that are both intuitive for human observation and resistant to counterfeiting.
Innovation Solution
A multilayer security element with a flat, transparent or translucent support coated with a variable optical effect layer, a dark opaque layer, a semi-reflecting layer, and a visible layer, where the semi-reflecting layer is reflective in reflection and transparent in transmission, and the visible layer is visible in both reflection and transmission, allowing for complex authentication without the limitations of vacuum deposition processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If vacuum-deposited metal layers are used to create security elements, then the layers can be made thin, shiny, and opaque with high reflectivity, but it is difficult to modify layer thickness during metallization to create adjacent opaque and semi-transparent areas
Solution Approach 1:
The patent divides the security element into multiple distinct layers with different optical properties (transparent substrate, opaque metallic layer with windows, semi-reflective layer, visible layer). This segmentation allows each layer to be optimized independently for its specific function, resolving the contradiction between achieving precise thickness control and maintaining manufacturing flexibility.
Solution Approach 2:
The patent transitions from a single-layer vacuum-deposited structure to a multi-layer construction where thickness variation is achieved not by modifying deposition parameters in real-time, but by strategically placing opaque and transparent regions across multiple layers. This dimensional approach to thickness control enables adjacent opaque and semi-transparent areas without requiring complex real-time parameter modification during metallization.
2Ease of manufacture
If a single opaque metallic layer is used, then the structure is simple to manufacture, but it cannot provide both opaque and semi-transparent adjacent areas with varying thicknesses
Solution Approach 1:
The security element is segmented into multiple functional layers: a transparent substrate layer, an opaque metallic layer with window openings, a semi-reflective layer, and a visible layer. This segmentation enables the structure to display both opaque and semi-transparent adjacent areas, providing versatile optical properties while maintaining manufacturing simplicity through standardized layer fabrication processes.
Solution Approach 2:
The patent employs composite material construction by combining materials with different optical properties (transparent polymer substrate, opaque metal, semi-reflective coating, colored visible layer) into a single security element. This composite approach achieves diverse optical characteristics including adjacent opaque and semi-transparent regions without requiring complex single-layer structures.
3Reliability
If complex authentication features are created to prevent counterfeiting, then security reliability increases, but the features become more difficult to observe and verify by naked eye
Solution Approach 1:
The patent incorporates a visible layer that displays distinct colors and patterns visible in both reflected and transmitted light. This layer provides immediate naked-eye verification of authenticity through color changes and optical effects, while the underlying complex multi-layer structure maintains high counterfeit resistance. The color-changing visible features make authentication simple while the complex layered construction ensures security reliability.
Solution Approach 2:
The patent enables dual-mode observation by constructing layers that interact with light in multiple dimensions - the semi-reflective layer provides reflection-based verification, while the transparent and opaque layers enable transmission-based verification. This multi-dimensional optical design allows complex authentication features to be observed and verified through both reflected and transmitted light, maintaining both security reliability and observation simplicity.
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 solution enhances the security and authenticity of banknotes by providing a complex, easily observable authentication feature that is difficult to reproduce, while allowing for precise control over layer thickness and appearance, improving detection of counterfeits.
Implementation Method 1
a semi-reflective layer, that is to say, which is reflective when the support is observed in reflected light, and which is transparent when the support is observed by transmission
Implementation Method 2
a layer with variable optical effect, that is to say, which, under observation of the support, provides at least one change in appearance visually perceptible to the naked eye, depending on the conditions of observation
Data Source
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AI summary
The present invention relates in particular to a multilayer security element (2), which comprises a transparent or translucent planar mounting (21), characterised in that one of the opposing faces of said mounting (21) is coated with the following consecutive layers: a) a layer with variable optical effect (22), i.e. which, under observation of the mounting (21), provides at least one change of appearance which is visible to the naked eye, in accordance with the observation conditions; b) a dark opaque layer (23) which has at least one slit (230); c) a semi-reflective layer (24), i.e. which is reflective when the mounting (21) is observed under reflected light, and which is transparent when the mounting is observed by transmission, said semi-reflective layer (24) being provided at least opposite one portion of said slit (230); d) a visible layer (25), i.e. which is visible under reflected light as well as by transmission, provided at least vertically in line with the one or more regions in which the semi-reflective layer (24) is provided.