Security Element With Inverted Layer Structure for Anti-Forgery
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing security elements for valuable documents lack effective protection against forgery, particularly in transmission mode, as they often rely on angle-dependent color effects that can be reproduced using conventional copying methods.
Innovation Solution
A security element with a flat, transparent body featuring a basic grid structure that provides different color impressions when viewed from the front and back due to inverted layer configurations, exploiting the principle of reciprocity in light path transmission, ensuring the motif is visible only in reflection and not in transmission, regardless of viewing angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If angle-dependent color effects are used in security elements, then color saturation is improved, but the security against forgery deteriorates because conventional copying methods can reproduce them
Solution Approach 1:
The patent applies asymmetry by creating a basic element structure that is not symmetric with respect to the central plane, where the arrangement of high-index dielectric elements differs between the front and back sides. This asymmetric configuration causes the structure to interact differently with light incident from the front versus light incident from the back, producing different color impressions in each direction while maintaining angle insensitivity
Solution Approach 2:
The patent employs inversion by designing the basic element structure such that the layer configuration is inverted between front and back sides. Specifically, the high-index dielectric elements are positioned at different heights relative to the central plane when viewed from front versus back, creating reciprocal color effects that are fundamentally different in each direction, making forgery detection possible
2Illumination intensity
If subwavelength grating structures are used to achieve color filtering, then color effect is improved, but the structure complexity increases
Solution Approach 1:
The patent utilizes parameter changes by varying the height, width, and spacing of the high-index dielectric elements within the basic element structure. By adjusting these geometric parameters, the optical response of the structure can be tuned to produce desired color effects without changing the fundamental structure type, thereby achieving complex optical functionality with relatively simple structural modifications
Solution Approach 2:
The patent applies local quality by creating spatial variations in the basic element structure, where different regions contain high-index dielectric elements with different local configurations (different heights, widths, or spacing). This allows different areas of the security element to exhibit different color effects or optical properties, enabling multifunctional security features within a unified structure
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 security element achieves high protection against forgery by ensuring the motif is only visible in reflection and not in transmission, making it difficult to replicate using conventional methods, and can be produced using standard embossing processes.
Implementation Method 1
exploiting the principle of reciprocity in light path transmission
Implementation Method 2
the motif is visible only in reflection and not in transmission
Data Source
Figure 1a~2
Figure 3~5
Figure 6~7
AI summary
The invention relates to a security element for a valuable article, said security element having a flat, transparent body having a front side and a rear side, between which a central plane (M) is located, a first region (I) formed on the body and a second region (II) formed on the body, said regions coding a motif (21, 22), wherein the body has a basic element structure (G) in the first region, said basic element structure imparting different colour impressions from the front side and rear side when the body (1) is viewed in plan view, wherein the body likewise has the basic element structure (G) in the second region (II), but in a mirror-inverted form with respect to the central plane (M), with the result that the first and second regions (I, II) show the motif (21, 22) when both sides are viewed in plan view, but the motif (21, 22) is not detectable in transmitted light.