Optically Variable Security Element with Dual Relief Structures
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Solution Overview
Problem
Existing optically variable security elements with viewing angle-dependent effects are technologically demanding to manufacture and require fine screening, making them challenging to produce effectively.
Innovation Solution
An optically variable security element with a multi-colored reflective surface area featuring two independent relief structures at different heights, each coated with wavelength-dependent reflection and transmission layers, allowing for distinct optical effects when viewed from above and through, utilizing high-refractive index layers and micromirror arrangements for enhanced visibility and authenticity verification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a fine grid structure is used in the colored coating to enable seamless transition between appearances, then the optical effect quality is improved, but the manufacturing complexity increases significantly
Solution Approach 1:
The invention divides the single complex grid structure into two separate relief structures at different heights, each with its own coating. The higher relief structure has a first colored coating, and the lower relief structure has a second colored coating. This segmentation eliminates the need for a fine grid in a single layer, simplifying manufacturing while maintaining the seamless transition effect between different viewing angles.
Solution Approach 2:
The invention adds the vertical dimension (height difference) between two relief structures to achieve the optical transition effect. Instead of relying on a fine grid pattern in a single plane, the solution uses depth variation with the higher relief structure appearing at different angles than the lower relief structure, thereby simplifying the coating requirements while maintaining optical quality.
2Reliability
If multiple optically variable effects are combined in a single element, then the security verification capability is improved, but the manufacturing process becomes more demanding
Solution Approach 1:
The invention segments the multiple optically variable effects into two independent relief structures, each contributing a different optical effect. The higher relief structure provides one optically variable effect with its colored coating, while the lower relief structure provides another optically variable effect. This segmentation allows each structure to be manufactured independently using standard techniques, reducing overall manufacturing complexity while maintaining high security verification capability.
Solution Approach 2:
Each relief structure is given specific local properties: the higher relief structure has a first colored coating optimized for certain viewing angles, while the lower relief structure has a second colored coating optimized for other angles. This local differentiation allows each component to be manufactured with standard precision while the combination provides enhanced security through multiple optically variable effects.
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 an easily manufacturable, visually appealing security element that ensures authenticity by offering seamless color and effect changes when tilted, with distinct colors visible from different angles and an achromatic appearance when viewed through, enhancing security against unauthorized reproduction.
Implementation Method 1
The higher relief structure is provided with a first reflection-enhancing coating following the relief profile, which has a wavelength-dependent reflection and transmission in the visible spectral range and at least one reflection band and at least one transmission band
Implementation Method 2
The lower relief structure is provided with a second reflection-enhancing coating following the relief profile, which has a wavelength-dependent reflection and transmission in the visible spectral range and also has at least one reflection band and at least one transmission band
Implementation Method 3
The first reflection-enhancing coating preferably contains one or more high-index layers, preferably dielectric high-index layers, which have a refractive index of at least 1.7, preferably at least 2.0, and particularly preferably at least 2.2
Implementation Method 4
The first reflection-enhancing coating preferably contains one or more high-index layers, preferably dielectric high-index layers, which have a refractive index of at least 1.7, preferably at least 2.0, and particularly preferably at least 2.2
Data Source
Figure 1~2
Figure 3~3(c)
Figure 4
AI summary
The invention relates to an optically variable security element (12) having a reflective flat region (20), which, in front illumination, shows at least two optically variable effects which can be detected from different viewing directions and appear with different first and second colours, and which, in rear illumination, shows an image in a third different colour. According to the invention, the reflective flat region (20) contains two separate relief structures (24, 34) which form a lower and a higher relief structure and which overlap in a feature region. The higher and lower relief structure (24, 34) are each provided with a reflection-increasing coating (26, 36) which follow the course of the relief and which have a wavelength-dependent reflection and transmission in the visible spectral range and have at least one reflection band and at least one transmission band. One reflection band of the second reflection-increasing coating (26) is at least partially in a transmission band of the first reflection-increasing coating (36) and overlaps at least one transmission band of the two reflection-increasing coatings (26, 36).