Optically Variable Security Element with Microstructure and Layer Sequence
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Solution Overview
Problem
Current optically variable security elements lack a layer sequence and microstructure that effectively provides a motif visible from the top side while offering enhanced anti-counterfeiting features through viewing angle-dependent color effects.
Innovation Solution
An optically variable security element with a microstructure and layer sequence comprising a reflection layer and a viewing angle-dependent layer, where the microstructure is embossed on a carrier substrate with periodic structural elements that create a motif visible from above, and the layer sequence includes a reflection layer and a viewing angle-dependent layer system, which changes color based on the viewing angle, enhancing security features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If a microstructure with periodic structural elements is used to create a visible motif, then the motif visibility from the top side is improved, but the complexity of the layer sequence and microstructure increases
Solution Approach 1:
The security element is divided into distinct functional layers: a microstructure layer with periodic structural elements that creates the motif, a reflective layer that enhances visibility, and a viewing angle-dependent layer that provides color effects. Each layer performs a specific function, allowing the motif to be visible from the top side while managing complexity through functional segmentation.
Solution Approach 2:
The microstructure with periodic structural elements is embedded within a multi-layer configuration where the reflective layer and viewing angle-dependent layer are positioned relative to the microstructure. The structural elements are arranged at regular intervals within the layer sequence, creating a nested arrangement that achieves motif visibility while organizing complexity in a structured manner.
2Loss of information
If a reflective layer is added to make the motif visible, then the motif visibility is improved, but the device complexity increases
Solution Approach 1:
The reflective layer is integrated with the microstructure and viewing angle-dependent layer to form a unified security element. The reflective layer is positioned in relationship to the periodic structural elements, combining the motif-creating function of the microstructure with the visibility-enhancing function of the reflective layer in a single coordinated structure.
3Reliability
If a viewing angle-dependent layer is added to create color effects, then the anti-counterfeiting capability is improved, but the device complexity increases
Solution Approach 1:
The security element employs a composite layer sequence combining a microstructure with periodic structural elements, a reflective layer, and a viewing angle-dependent layer. Each layer contributes different optical properties: the microstructure creates the motif through diffraction and reflection, the reflective layer enhances visibility, and the viewing angle-dependent layer provides color effects that change with observation angle, together creating a complex anti-counterfeiting feature set.
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 secure and visually distinct motif that is visible from the top, with the reflection layer making the motif visible and the viewing angle-dependent layer creating a color effect, thereby enhancing the security element's anti-counterfeiting capabilities.
Implementation Method 1
The microstructure has structural elements that are arranged at regular intervals, i.e., periodically, with a period of 2 μm to 50 μm. Due to the period of 2 μm to 50 μm, diffraction phenomena have only a minimal impact on the optical properties.
Implementation Method 2
The reflective layer, in conjunction with the microstructure, ensures that the intensity of the incident light is altered, making the motif created by the microstructure clearly visible to the naked eye.
Implementation Method 3
The viewing angle-dependent layer creates a viewing angle-dependent (so-called OVD) color impression. The color of the area of the optically variable security element where the viewing angle-dependent layer is visible changes depending on the illumination or viewing direction.
Data Source
Figure 1~4
Figure 5~7
AI summary
The invention relates to an optically variable security element which, viewed from the top, has a layer sequence. The layer sequence contains a micro-structure (2) which provides a motif that is visible from the top, and which micro-structure has a period of 2 μm to 50 μm and is achromatic. Furthermore, the layer sequence has a reflective layer (4) that is arranged on the micro-structure (2) and reflects incident light, and has a viewing-angle-dependent layer (6; 14). The reflective layer (4) or the viewing-angle-dependent layer (6; 14) has at least one recess (15), and the other one of the two is unstructured. That layer that has the recess (15) lies on top of the other layer, which is unstructured, as viewed from the top. Instead of the recess and the reflective layer, the security element can have an unstructured, viewing-angle-dependent layer (6; 14) and an unstructured, semi-reflective reflective layer (16; 18).