Visually Variable Security Element with Two-Layer Color Mirror
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Solution Overview
Problem
Existing optically variable security elements are costly to produce due to thick dielectric spacer layers and struggle to combine color mirrors with register-accurate, colorless negative text elements, leading to undesirable build-up and limited versatility in reflective colors.
Innovation Solution
A two-layer color mirror comprising a reflective metal layer and an ultra-thin absorber layer made of silicon or its alloys, with varying layer thicknesses to achieve a wide range of reflection colors, combined with a relief structure to create an optically variable and attractive appearance, allowing for cost-effective production and integration with non-metallic color impressions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If thick dielectric spacer layers (200-400 nm) are used to achieve color shift effects, then the optical thickness can be controlled, but production becomes time-consuming and expensive
Solution Approach 1:
The patent changes the thickness parameter of the dielectric spacer layer from conventional thick (200-400 nm) to ultra-thin (1-200 nm). This parameter change enables the same optical thickness control function to be achieved with much thinner layers, reducing material usage and production time while maintaining the color shift effect through precise thickness control in the nanometer range
Solution Approach 2:
The patent replaces expensive, time-consuming thick dielectric spacer layer production with cheaper, faster ultra-thin layer deposition. The ultra-thin absorber layer can be produced more rapidly using modern deposition techniques, making the security element more cost-effective while maintaining optical functionality
2Ease of manufacture
If colored semi-transparent paints are applied to metal surfaces, then color mirrors can be formed, but register-accurate and colorless negative text elements cannot be easily combined
Solution Approach 1:
The patent segments the color mirror structure into two distinct layers: a reflective metal layer and a separate ultra-thin absorber layer. This segmentation allows independent optimization and processing of each layer, enabling the absorber layer to be selectively removed or patterned to create register-accurate negative text elements without affecting the underlying metal layer, thus achieving both color mirror effects and text integration
Solution Approach 2:
The ultra-thin absorber layer acts as an intermediary between the metal layer and the viewer. It can be selectively removed in specific areas to create transparent or reflective regions for negative text, while remaining intact in other areas to provide color filtering. This intermediary layer enables versatile design combinations without compromising either color mirror formation or text element integration
3Ease of manufacture
If lacquer layers are applied to metal surfaces, then color mirrors can be created, but the additional thickness leads to stronger build-up which is disadvantageous
Solution Approach 1:
The patent dramatically changes the thickness parameter of the absorber layer from conventional lacquer layer thickness (typically micrometers) to ultra-thin thickness (1-200 nm). This parameter change reduces the layer thickness by factors of 10-100 times, eliminating the unwanted build-up effect while maintaining the color filtering function through precise nanometer-scale thickness control
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 enables the production of cost-effective optically variable security elements with high security against forgery, offering a range of reflective colors and seamless integration with non-metallic elements, enhancing authenticity verification.
Implementation Method 1
an ultra-thin absorber layer made of silicon, a silicon alloy or SiOx with x < 2, in particular amorphous silicon, which is applied to the relief structure together with the metal layer or applied to the metal layer
Implementation Method 2
a reflective metal layer and an ultra-thin absorber layer made of silicon, a silicon alloy or SiOx with x < 2... together produce an optically variable and colored appearance in reflection
Implementation Method 3
The color shift effect of such thin-film elements is based on viewing angle-dependent interference effects due to multiple reflections in the various sub-layers of the element
Data Source
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AI summary
The invention relates to a visibly variable security element (12) for securing valuable objects, wherein a relief structure (22) and a two-layer color mirror (30) are arranged one over the other and, in interaction, produce a visually variable and colored appearance in reflection, wherein the two-layer color mirror (30) consists of a reflective metal layer (32) and an ultra-thin absorber layer (34), which is arranged on the metal layer (32) and consists of silicon, a silicon alloy, or SiOx with x < 1.