Security Device with Contour-Following Reflection Layer
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Solution Overview
Problem
Existing security devices with optically variable effects, such as holograms and diffraction gratings, face challenges in enhancing security and cost-effectiveness, particularly with the use of multiple metals which are expensive and limited in color options, and brittle materials that reduce durability in flexible documents.
Innovation Solution
A security device featuring a transparent, colored element with an optically variable effect generating relief structure and a reflection enhancing layer that follows the contour of the relief, with the layer also present in a second region laterally offset, providing a multi-colored effect and enhanced security through the use of a metal or high refractive index layer, and a method involving curable materials and hot stamping processes that allow for flexible and durable application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two or more metals are used in intimate contact with the surface relief to spatially modulate the hologram or diffraction grating, then the security is enhanced by varying the intensity of diffractive light in an unconventional and difficult to replicate manner, but the manufacturing complexity and cost increase and the choice of colours is limited
Solution Approach 1:
The patent extracts the reflection-enhancing function from complex multi-metal structures and implements it through a single simplified layer applied over the entire surface relief. This single layer can be a metal, metallic, or high refractive index material that follows the contour of the relief, eliminating the need for multiple metals in intimate contact while maintaining the optically variable effect and security features.
Solution Approach 2:
The patent changes the material parameter from multiple metals with limited color options to a single layer that can be applied in various colors. The reflection-enhancing layer can be provided in different colored regions, allowing for greater color variety and design flexibility while simplifying the manufacturing process.
2Illumination intensity
If vapour deposited metals are used to provide the reflection enhancing layer, then the optically variable effect is enhanced, but the choice of colours is very limited
Solution Approach 1:
The patent changes the material parameter from vapour deposited metals with limited color options to a single reflection-enhancing layer that can be applied in various colors through different deposition methods or colored materials. This allows the same structural approach to achieve diverse color effects while maintaining high optical reflection intensity.
Solution Approach 2:
The patent employs composite material approaches where the reflection-enhancing layer can be a metal, metallic, or high refractive index material, or combinations thereof. This composite approach enables greater color versatility while maintaining the enhanced optically variable effect.
3Ease of manufacture
If a single reflection enhancing layer is used over the optically variable effect generating relief structure, then the manufacturing is simplified and cost is reduced, but the security enhancement may be insufficient
Solution Approach 1:
The patent applies local quality by providing the reflection-enhancing layer in specific colored regions corresponding to different areas of the optically variable effect. The layer can have different colors in different regions, allowing for localized security features and enhanced verification capabilities while maintaining overall manufacturing simplicity.
Solution Approach 2:
The patent enhances security through parameter changes by varying the color, refractive index, or optical properties of the reflection-enhancing layer in different regions. This creates complex optically variable effects that are difficult to replicate while using a single-layer structure that remains manufacturable.
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 enhances the security and aesthetic appeal of optically variable devices by providing a multi-colored effect with increased durability and flexibility, allowing for complex and secure designs on documents like banknotes and passports without the need for expensive multi-metal solutions, while maintaining the optically variable effects.
Implementation Method 1
hologram or diffraction grating is spatially modulated
Implementation Method 2
varies the intensity of the diffractive light
Implementation Method 3
reflection enhancing layer extending over the first optically variable effect generating relief microstructure and following the contour of the relief
Implementation Method 4
transparent, coloured element in a first region of the device
Implementation Method 5
high refractive index layer such as ZnS
Data Source
AI summary
A security device comprises a transparent, colored element in a first region of the device and in a surface of which a first optically variable effect generating relief structure is formed. A reflection enhancing layer extends over the first optically variable effect generating relief microstructure and follows the contour of the relief, the reflection enhancing layer also being provided in a second region of the device laterally offset from the first region.