Security Element with Overlapping Optical Coatings
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Solution Overview
Problem
Existing security elements for value and security documents, such as banknotes and ID cards, face challenges in providing effective copy protection due to complex and costly production processes, which are compromised by advanced digital reproduction techniques, limiting their security against forgery.
Innovation Solution
A security element featuring a first and second periodic optical structure on opposite sides of a transparent layer, arranged to overlap at specific viewing angles, creating a color change effect using different colors and luminescent pigments, which can be produced using cost-effective printing technologies without surface structuring, enhancing security against forgery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional hologram or surface-structured security elements are used, then copy protection effectiveness is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The invention extracts the security function from complex surface structures and holograms, replacing them with simple planar coatings containing luminescent pigments. The security effect is achieved not through structural complexity but through the optical properties of the pigment layers themselves, which can be applied using standard printing techniques.
Solution Approach 2:
The patent employs inexpensive luminescent pigments and standard printing materials instead of expensive holographic foils or specialized surface-structuring components. This approach uses readily available, cost-effective materials that can be applied through conventional printing processes, significantly reducing manufacturing costs while maintaining security functionality.
2Ease of operation
If tilting effect security elements are used, then visual verification is improved, but digital reproduction resistance deteriorates
Solution Approach 1:
The invention uses luminescent pigments that exhibit color changes under different illumination conditions (visible light vs. UV light). This color transformation provides a clear visual verification mechanism for humans while creating patterns that do not reproduce well in digital copying, as scanners and cameras typically operate in the visible spectrum and cannot capture the UV-induced luminescence.
Solution Approach 2:
The security element employs periodic line structures with specific frequencies that create moiré effects when viewed under different conditions. These periodic patterns provide distinct visual characteristics for human verification while being difficult to reproduce accurately in digital copies, especially when combined with the luminescent color-change property.
3Reliability
If multiple halftone line structures with different frequencies are superimposed, then moiré pattern creation is improved, but visual design options and verification ease are reduced
Solution Approach 1:
Instead of relying solely on complex multi-frequency halftone superposition, the invention uses luminescent pigments that change color under UV illumination. This provides a straightforward visual verification method where the entire pattern transforms color, offering greater design flexibility and easier verification compared to analyzing multiple overlapping halftone frequencies.
Solution Approach 2:
The security element incorporates luminescent pigments that automatically respond to UV light exposure, creating the security effect in advance without requiring complex real-time verification processes. The color change occurs immediately upon UV exposure, providing a pre-programmed security response that is both reliable and easy to verify.
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 solution provides a highly secure, cost-effective means of producing a color-changing security element that is difficult to replicate, offering a high degree of protection against counterfeiting, especially when the colors are difficult to separate, and creates a 3D effect that disappears in digital reproduction.
Implementation Method 1
the first optical structure and the second optical structure are arranged so that they overlap so that an outside observer from a specific, predetermined viewing angle to the surface of the transparent layer provided with the coatings or illumination angle of the light source used for verification, in particular a UV lamp, shows a color change effect
Data Source
AI summary
The present invention relates to a security element for a document of value and/or a security document which is arranged on a transparent layer, for example a film (1, 1'), wherein the security element has a first periodic, optical structure, for example a grid of lines (10, 30, 30') or a grid of points, which forms a first coating on the first side of the transparent layer, and a second periodic, optical structure, for example a grid of lines (20, 40, 40', 40'') or a grid of points, which forms a second coating on the second side, opposite from the first side of the transparent layer. In order to achieve better protection against copying, the first optical structure and the second optical structure are preferably arranged as overlapping in such a way that, when seen by an outside observer from a certain, predetermined viewing angle (α) or lighting angle, they show a colour-changing effect, wherein the first coating has a first colour and the second coating has at least one second colour that is different from the first colour.