Security Element Multilayer Structure Optical Effects
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Solution Overview
Problem
Existing security elements for papers and documents suffer from complexity in production and lack of effective anti-counterfeiting features, particularly when viewed from the back in transmitted light, where they often produce a uniform gray color rather than providing distinct visual effects.
Innovation Solution
The security element features a reflection layer formed by a color layer with platelet-shaped metallic particles or a multi-layer structure comprising semi-transparent mirror layers and a dielectric layer, which exhibits a metallic color in reflected light and a blue color in transmitted light, eliminating the need for recesses and enhancing the color-shifting effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a large number of cutouts are introduced into the partially transparent layer and reflective layer to create different optically variable effects, then diverse optical effects are achieved, but the manufacturing complexity increases significantly
Solution Approach 1:
The invention extracts and eliminates the cutouts from the partially transparent layer and reflective layer. Instead of creating complexity through numerous cutouts, the patent uses a continuous layer structure with controlled optical properties to achieve the desired visual effects, thereby simplifying manufacturing while maintaining optical versatility
Solution Approach 2:
The invention changes the optical parameters of the layers by using specific refractive indices and thicknesses. The partially transparent layer has a refractive index of 1.3-1.7 and the dielectric layer has a refractive index of 1.4-2.1, with carefully controlled thickness ratios that produce the desired optical effects without requiring complex cutout patterns
2Adaptability or versatility
If a large number of cutouts are introduced into the partially transparent layer and reflective layer to create different optically variable effects, then diverse optical effects are achieved, but the production process becomes more difficult
Solution Approach 1:
The invention removes the cutout feature entirely from the design. The continuous layer structure without cutouts is much easier to manufacture using standard deposition techniques, while the optical effects are achieved through the inherent optical properties of the layered structure rather than geometric modifications
Solution Approach 2:
The invention uses homogeneous continuous layers instead of heterogeneous structures with numerous cutouts. The uniform composition and continuous structure of each layer simplify the manufacturing process while the controlled optical properties of the homogeneous layers produce the desired visual effects
3Adaptability or versatility
If a large number of cutouts are introduced into the partially transparent layer and reflective layer, then different optically variable effects are created in plan view, but the elements produce only a uniform gray hue when viewed from the back in transmitted light
Solution Approach 1:
The invention applies different optical properties to different layers locally. The partially transparent layer with its specific refractive index and thickness is optimized for transmitted light viewing, while the dielectric and reflective layers are optimized for reflected light viewing. This local optimization ensures that each layer contributes appropriately to both viewing modes without compromising either
Solution Approach 2:
The invention shifts from relying on two-dimensional cutout patterns to utilizing the third dimension of layer thickness and refractive index control. By optimizing the thickness and optical properties of each layer, the invention achieves diverse optical effects in reflected light while maintaining appropriate transmission characteristics, adding a dimensional parameter for optical 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
This configuration enhances the color-shifting effect in reflected light while maintaining a consistent blue color in transmitted light, thereby increasing protection against counterfeiting and simplifying production processes.
Implementation Method 1
The color shift is caused by an interference effect between the light rays reflected from the surface of the outer semi-transparent layer and the light rays passing through the outer semi-transparent and middle dielectric layers and reflected back to the semi-transparent layer by the reflective layer
Implementation Method 2
the color layer contains platelet-shaped metallic particles whose longest edge length is 15 nm to 1000 nm and whose thickness is 2 nm to 100 nm, so that the color layer exhibits a golden hue in reflected light and a blue hue in transmitted light
Data Source
Figure 1~2
Figure 3a~3b
AI summary
The invention relates to a security element for security papers, value documents, or the like, which consists of a mutlilayer structure capable of interference, wherein the multilayer structure capable of interference has a reflection layer, a dielectric layer, and a partially transparent layer, wherein the dielectric layer is arranged between the reflection layer and the partially transparent layer. According to the invention, the reflection layer of the multilayer structure capable of interference is formed by a colored layer or a further multilayer structure, wherein the colored layer and the multilayer structure are designed in such a way that the colored layer and the multilayer structure exhibit a metallic shade in incident light and a colorful shade in transmitted light.