Optically Variable Security Element with Diffraction Structure
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Solution Overview
Problem
Current optically variable security elements with kinematic/stereographic effects based on micromirror structures are costly and limited in color effects, as they require vacuum vapor deposition processes and have a narrow range of possible color changes, which are isotropic and not direction-dependent.
Innovation Solution
A reflective surface area with a diffraction structure formed by additively superimposing a macroscopically or microscopically fine relief structure and a microscopically fine perforation pattern, where the relief structure and perforation pattern work together to create a light-diffracting or light-scattering effect, allowing for a wide range of color changes and visual effects when tilted, while being cost-effective and providing high security against forgery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If vacuum vapor deposition processes are used to produce color-changing coatings on micromirror structures, then coloring can be provided, but the process is time-consuming and costly
Solution Approach 1:
The patent replaces the vacuum vapor deposition process (physical/chemical process) with a relief structure approach where color effects are achieved through geometric optics and light diffraction. The relief structure with varying heights and orientations creates color changes through selective light reflection and diffraction, eliminating the need for complex vacuum deposition equipment and processes.
Solution Approach 2:
The patent changes the approach from material-based coloring (vacuum deposition coatings) to structure-based coloring. By varying the relief structure parameters (height, orientation, shape) across different regions, the patent achieves color effects without requiring actual colorants or coatings. The color change is produced by the geometric configuration of the relief structure itself.
2Adaptability or versatility
If additional color-shifting coatings are applied to micromirror structures, then color effects can be achieved, but the range of possible color effects is limited and always isotropic
Solution Approach 1:
The patent divides the security element into multiple relief structures with different orientations and height profiles. Each relief structure can be independently designed to produce specific color effects when viewed from certain angles. This segmentation allows for a wide range of color effects without requiring complex multi-layer coatings, as each segment contributes differently to the overall optical effect.
Solution Approach 2:
The patent employs asymmetric relief structures with varying heights and orientations that are not uniformly distributed. This asymmetry enables the structure to produce different color effects depending on the viewing angle and tilt direction. The asymmetric design allows for anisotropic color changes (direction-dependent) rather than isotropic changes, expanding the range of possible color effects.
3Ease of operation
If micromirror structures with size above 5 μm are used, then kinematic/stereographic effects can be achieved, but the structures themselves do not produce color effects
Solution Approach 1:
The patent merges the kinematic effect (from micromirror structures) with color effects (from relief structure diffraction) into a single integrated security element. The relief structure is designed to work in conjunction with the micromirror array, where the relief structure provides the color effects while the micromirrors provide the kinematic effects. This combination achieves both functional requirements without requiring separate components.
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 cost-effective optically variable security element with a high degree of security against forgery, offering attractive visual appearances and allowing for creative design freedom, with tilting effects that are decoupled and direction-dependent, enhancing authenticity verification.
Implementation Method 1
a diffraction structure which is formed by additively superimposing a macroscopically or microscopically fine relief structure and a microscopically fine perforation pattern, the diffraction structure being created by a structure function S(x,y)
Implementation Method 2
the perforation pattern is formed by a reflective layer with a large number of microscopically fine perforations which, due to the additive superimposition, follows the course of the relief structure and represents a light-diffracting or light-scattering optically effective and partially transparent coating of the relief structure
Implementation Method 3
the perforation pattern is formed by a reflective layer with a large number of microscopically fine perforations
Data Source
Figure 1~2
Figure 3(a)~4
Figure 5(a)~6
AI summary
The invention relates to an optically variable security element (12) for securing valuables, with a carrier having a reflective surface area (20) whose extent defines an xy-plane and a z-axis perpendicular to it. According to the invention, it is provided that: - the reflective surface area (20) is partially transparent and has a diffraction structure (30) formed by an additive superposition of a macroscopically or microscopically fine relief structure (32) and a microscopically fine perforation pattern (40), wherein the diffraction structure (30) is described by a structure function S(x,y), the relief structure (32) by a relief function R(x,y), the perforation pattern (40) by a pattern function P(x,y), and the additive superposition is described by S(x,y) = R(x,y) + P(x,y), - the perforation pattern (40) is formed by a reflective layer with a plurality of microscopically fine perforations (42).which, due to the additive superposition, follows the course of the relief structure (32) and represents a light-diffracting or light-scattering optically effective and partially transparent coating of the relief structure (32), and - the relief function R(x,y) describing the relief structure (32) is at least piecewise continuous, does not represent a periodic triangular or rectangular function and changes only slowly compared to the pattern function P(x,y).