Multi-layer Security Element with Microstructure Grid
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Solution Overview
Problem
Existing multi-layer security elements for documents, such as banknotes and ID documents, lack novel optically variable effects, making them susceptible to imitation and reproduction through holographic copying or mechanical molding.
Innovation Solution
A multi-layer body with specific microstructure designs and layer configurations that create unique optically variable effects by varying the dimensions, orientations, and spatial frequencies of microstructures and microimages, providing high protection against imitation and reproduction through the use of diffractive and refractive structures, and varying layer thicknesses to achieve striking, bright, and contrast-rich visual effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional optically variable security elements are used, then security documents can be protected to some extent, but they are susceptible to imitation and reproduction through holographic copying or mechanical molding
Solution Approach 1:
The security element is divided into multiple layers (first layer with microimages, second layer with microstructures, third layer as reflection layer) where each layer performs a specific optical function. This segmentation creates complex optically variable effects that are difficult to replicate through conventional copying methods.
Solution Approach 2:
The patent introduces a third dimension by creating a multi-layer body with specific spacing between layers (5-150 μm). The microstructures in the second layer are designed to reflect light back to specific areas of the first layer, creating depth effects and novel optical phenomena that cannot be achieved with conventional two-dimensional security elements.
2Illumination intensity
If the area proportion of first zones is increased to enhance optically variable effect visibility, then the security element becomes more striking and bright, but the transmission of the layer decreases
Solution Approach 1:
The first layer is designed with locally differentiated zones: first zones (20-80% area proportion) containing microimages with specific optical properties, and second zones providing contrast. This local quality differentiation allows optimization of optical effects in specific areas while maintaining overall transmission characteristics.
Solution Approach 2:
The security element uses composite layering with different materials and optical properties: transparent first layer with microimages, transparent second layer with microstructures, and reflective third layer. This composite structure enables simultaneous optimization of brightness, contrast, and transmission by leveraging the complementary properties of different layers.
3Ease of manufacture
If microstructures and microimages are horizontally aligned, then the design is simple and manufacturing is easier, but no depth effect occurs
Solution Approach 1:
The patent creates dynamic optical effects by designing microstructures that respond to viewing angle changes. The microstructures are configured to reflect light back to specific areas of microimages depending on the observation angle, creating moving images and depth effects that change as the viewer moves, thereby adding visual complexity without complicating the static manufacturing process.
4Adaptability or versatility
If the spacing between the first layer and reflection layer is increased to enhance viewing angle dependency, then the optically variable effect becomes more marked, but the layer thickness increases
Solution Approach 1:
The patent optimizes the spacing parameter between the first layer and reflection layer within a specific range (5-150 μm). This parameter optimization achieves the desired viewing angle dependency and optical effect intensity while controlling the overall layer thickness. The microstructure design further fine-tunes the optical properties to maximize effect strength within the constrained thickness.
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 generates novel optically variable effects with high brilliance and depth, making it difficult to replicate, thereby enhancing security against copying and imitation, and providing a distinctive and memorable security feature.
Implementation Method 1
the microstructures are designed and/or the layer thickness of the second layer is selected in such a way that light incident on the microstructures perpendicularly with respect to the plane spanned by the first layer from the direction of the first layer in the area of the respective third zone reflects back
Implementation Method 2
the light incident on the microstructures perpendicularly with respect to the plane spanned by the first layer from the direction of the first layer in the area of the respective third zone reflects back and/or diffracts back
Data Source
Figure 1~3b
Figure 4
Figure 5~6
AI summary
The invention relates to a multi-layer body (1) comprising a first layer (13) having a plurality of first zones (21), which are separated from each other by one or more transparent second zones (22). The multi-layer body comprises a second layer (14), which is made of a transparent material and is arranged below the first layer (13), and a reflective layer (15), which is arranged below the second layer (14). The second layer (14) comprises a plurality of third zones (23), in each of which a microstructure (17) is formed in the bounding surface of the second layer (14) to the reflective layer (15), which bounding surface faces away from the first layer. Each of the microstructures (17) is designed in such a way that light incident perpendicularly, relative to the plane spanned by the first layer, in the region of the respective third zone (23) from the direction of the first layer, is reflected or refracted back to a region of the first layer by the microstructure, the area of which region is less than the area of the respective third zone (23) by a factor of at least 10. The microstructures (17) are arranged according to a microstructure grid having a distance between adjacent microstructures in a second spatial direction of less than 300 µm.