Variable-Geometry Coextruded Foils for Complex Security Features
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Solution Overview
Problem
Existing security features in value documents, such as credit cards, can be easily reworked and do not provide a reliable security feature, as conventional strip foils with equal widths can be manufactured using commercially available extruders.
Innovation Solution
A method for manufacturing a foil with a variable strip geometry by extruding surfaces orthogonally to the extrusion direction, varying their geometry, and using different materials and colors to create complex patterns that are difficult to replicate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional coextrusion methods are used to manufacture strip foils with equal width strips, then the manufacturing process is simple and commercially available extruders can be used, but the security feature is weak and can be easily reworked
Solution Approach 1:
The patent applies dynamics by making the extrusion system adjustable and variable rather than fixed. The distributor rail can be repositioned to create different strip width patterns, and the extrusion process can produce periodically modulated structures with varying geometries. This dynamic capability allows the same extrusion system to produce complex, secure patterns while maintaining manufacturing flexibility
Solution Approach 2:
The patent changes physical parameters of the extrusion process, specifically the position of the distributor rail and the geometry of the extruded strips. By varying the rail position and strip dimensions (width, length, spacing), the system creates complex patterns that are difficult to replicate. These parameter changes transform a simple extrusion process into one that produces secure, variable geometry foils
2Reliability
If simple strip patterns are used in value documents, then the manufacturing process is easy and conventional methods can be applied, but the documents are vulnerable to forgery and reworking
Solution Approach 1:
The patent applies asymmetry by creating strip patterns with unequal widths and irregular geometries rather than uniform repeating patterns. The periodically modulated structures feature varying strip dimensions that break symmetry, making the security feature visually distinctive and difficult to replicate with conventional equipment designed for uniform strip production
Solution Approach 2:
The system uses dynamic adjustment of the distributor rail position to create variable geometry patterns. This allows precise control over strip dimensions and spacing, producing complex patterns that require high manufacturing precision but provide superior forgery resistance through their irregular, non-repeating characteristics
3Reliability
If complex security features are introduced into value documents, then forgery resistance improves, but the manufacturing process becomes more difficult and requires specialized equipment
Solution Approach 1:
The patent achieves universality by designing an extrusion system that can produce multiple pattern types through a single device. The adjustable distributor rail and variable geometry capabilities allow one extrusion system to create various strip patterns and periodically modulated structures, eliminating the need for multiple specialized extruders and simplifying manufacturing 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
The method produces a foil with unique, complex patterns that serve as a secure feature, requiring significant effort to reproduce, enhancing the forgery-proof nature of value documents.
Implementation Method 1
an extrusion is effected of at least one first surface and at least one second surface, in such a manner that the surfaces form the foil in a sequence that alternates orthogonally to the extrusion direction
Data Source
AI summary
The invention is directed to a method for manufacturing a foil having a variable strip geometry, which makes it possible to supply a foil that bears a complex security feature. The varying of the geometry is effected by means of an adaptation of a melt flow of the extruder.