Integrated Diffractive and Interference Security Elements
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Solution Overview
Problem
Existing security elements, such as banknotes, are vulnerable to counterfeiting as they can be imitated by combining separate holographic and interference elements, which can be cut and assembled to resemble the genuine article.
Innovation Solution
A security element is created by combining an iridescent amplitude interference device with a cyclical reflective or diffractive device, enhancing the apparent integration of the two devices. This is achieved by arranging the devices such that they appear anisotropic, with the iridescent amplitude interference material exhibiting a rapid color change when tilted front-to-back and little to no change when tilted left-to-right, while the diffractive device shows color changes at low tilt angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate holographic and interference elements are combined, then the security level is improved, but the element becomes vulnerable to counterfeiting by cutting and assembling
Solution Approach 1:
The patent combines a diffractive or reflective relief structure with an iridescent amplitude interference material in a single integrated security element. The relief structure is formed on a substrate and the interference material is applied over it, creating a unified device where both optical effects coexist and are difficult to separate, thereby preventing counterfeiting through cutting and assembly while maintaining high security level.
Solution Approach 2:
The security element uses a composite structure combining two different optical mechanisms: a diffractive or reflective relief structure (first optically variable device) and an iridescent amplitude interference material (second optically variable device). This composite design integrates materials with different optical properties in a single element, making it highly difficult to replicate since counterfeiters would need to reproduce both effects and their precise spatial relationship.
2Ease of manufacture
If iridescent amplitude interference material is used, then color change effect is achieved, but the effect is only visible at specific tilt angles
Solution Approach 1:
The patent creates a dynamic optical display where the relief structure and interference material work together to produce different visual effects at different tilt angles. The relief structure provides optically variable effects (such as holographic replay or diffractive colors) that are visible at low tilt angles, while the interference material provides color change effects that become prominent at higher tilt angles, creating a continuous dynamic display that adapts to viewing conditions.
Solution Approach 2:
The security element incorporates an iridescent amplitude interference material that produces color change effects when tilted. This material is applied over a relief structure that provides additional optically variable effects. The combination ensures that color changes are visible across a range of tilt angles, with the relief structure providing visual interest at low angles and the interference material providing prominent color shifts at higher angles.
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 combined security element displays a complex, functionally linked visual effect that is difficult to replicate, significantly increasing the difficulty of producing a counterfeit version. The element maintains an optically variable effect from low tilt angles, with an additional color change at higher tilt angles, providing a high security level.
Implementation Method 1
a diffractive or reflective relief structure present at least in first partial areas of the region
Implementation Method 2
a diffractive or reflective relief structure present at least in first partial areas of the region
Implementation Method 3
a reflection enhancing material provided in the first partial areas of the region and being disposed on and following the contours of the diffractive or reflective relief structure
Implementation Method 4
a light absorbing material provided in second partial areas of the region which do not overlap the first partial areas
Implementation Method 5
iridescent amplitude interference material at least over the second partial areas of light absorbing material
Implementation Method 6
Thin film interference structures comprise repeating layers of different refractive indices; examples can include purely dielectric stacks (metal oxide or polymer) or those composed of alternate dielectric and metallic layers
Data Source
Figure 1~5
Figure 2(a)~2(b)
Figure 3(a)~4(b)
AI summary
A security element is provided comprising a substrate on which is disposed: in a first area, a first optically variable device comprising a diffractive or reflective relief structure and a reflection enhancing material following the contours of the relief structure; and, in a second area, a second optically variable device comprising an iridescent amplitude interference material. The first optically variable device is constituted by a plurality of sub-areas arranged in a cyclically repeating sequence along a predetermined direction of the security element, the plurality of sub-areas collectively forming the first area. The relief parameters of the diffractive or reflective relief structure vary from one sub-area to the next within each repeat cycle whereby, at any one viewing angle, each sub-area within any one repeat cycle exhibits a different diffractive colour or reflected intensity from those of the other sub-areas within the same repeat cycle, such that, when the device is tilted, the different diffractive colours or reflected intensities appear to move from one sub-area to the next within each repeat cycle along the predetermined direction.