Optically Variable Element Using Overlapping Facets and Subwavelength Structures
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Solution Overview
Problem
Existing optically variable security elements for value objects lack cost-effective and high-security features against forgery, particularly in generating observation angle-dependent three-dimensional effects that are difficult to reproduce.
Innovation Solution
An optically variable representation element with reflective surface regions containing overlapping reflective facets and subwavelength structures, which create different colors and three-dimensional impressions when viewed from different angles, using a micromirror arrangement and reflection-enhancing coatings to simulate curved surfaces and provide a 2½-dimensional representation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional security elements use multiple relief structures at different height levels with color coatings, then observation angle-dependent three-dimensional effects are achieved, but manufacturing complexity and production costs increase
Solution Approach 1:
The reflective surface is divided into multiple facets with different orientations, where each facet reflects light from specific observation angles. This segmentation allows the creation of multiple three-dimensional representations without requiring complex multi-level relief structures, thus reducing manufacturing complexity while maintaining security effectiveness
Solution Approach 2:
The patent transitions from traditional three-dimensional relief structures to a two-dimensional surface with strategically oriented facets. By arranging facets at different angles on a flat or mildly curved surface, the patent achieves observation angle-dependent three-dimensional effects without the manufacturing complexity of multi-level relief structures
2Reliability
If multiple relief structures with color coatings are used to create observation angle-dependent effects, then security against forgery is enhanced, but production costs increase
Solution Approach 1:
The patent combines multiple functions into a single integrated structure: the facets serve both as reflective elements for creating three-dimensional representations and as the structural basis for color differentiation through subwavelength structures. This merging eliminates the need for separate color coating layers on multiple relief structures, reducing production steps and costs
Solution Approach 2:
The patent uses subwavelength structures with varying parameters (period, depth, shape) on different facets to create different color impressions. By controlling these parameters rather than using multiple physical relief structures with different color coatings, the patent achieves color variation at lower manufacturing cost
3Reliability
If facets are oriented to create overlapping three-dimensional representations with different colors, then visual appearance and security are improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies different subwavelength structure parameters (period, depth, shape) to different facets to create locally differentiated color properties. This local quality approach allows for color differentiation without requiring extremely precise facet orientation, as the color is determined by the subwavelength structure parameters rather than exact angular alignment
Solution Approach 2:
The patent combines facets with subwavelength structures to create a composite structure where the optical properties are determined by the interaction of these elements. This composite approach allows for flexible control of both three-dimensional representation and color properties, reducing the stringency of manufacturing precision requirements compared to traditional single-structure approaches
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 a visually striking and secure three-dimensional representation that is difficult to reproduce, offering high forgery protection while reducing production costs by using fewer material layers and work steps compared to traditional designs.
Implementation Method 1
The at least one reflective surface region contains a plurality of reflective facets for this purpose in each case in a first and a second subregion, which at least partially overlap one another, which facets are oriented so that on the one hand the facets of the first subregion for the observer from the first observation direction create a first three-dimensional representation
Implementation Method 2
The facets of the reflective surface region are provided at least in some regions with subwavelength structures here in the overlap region of the first and second subregion, which create the different colors of the three-dimensional representations
Implementation Method 3
The facets of the reflective surface region are provided at least in some regions with subwavelength structures here in the overlap region of the first and second subregion, which create the different colors of the three-dimensional representations
Implementation Method 4
The facets of the reflective surface region are provided with a reflection-enhancing coating, in particular with a metallization, a highly-refractive layer, and/or a thin-film structure
Data Source
AI summary
An optically variable representation element with a reflective surface region generates a respective three-dimensional representation for at least two different observation directions. The reflective surface region contains a respective multiplicity of reflective facets in a first and a second partial region, which at least partially overlap one another. The reflective facets are oriented such that the facets in the first partial region generate a first three-dimensional representation from the first observation direction and the facets in the second partial region generate a second three-dimensional representation from the second observation direction. The facets of the reflective surface region are provided at least regionally with sub-wavelength structures which generate the different colors of the three-dimensional representations in the overlap region.