Polymer Foil Stack for Curved Synthetic Integral Images
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Solution Overview
Problem
Existing optical devices with synthetic images are limited to planar surfaces, deteriorating when applied to curved surfaces, and lack unique security features that are easy to detect but difficult to copy.
Innovation Solution
A polymer foil stack with optically distinguishable image data bearer structures and focusing elements, arranged in specific arrays with varying distances and angles, allowing for a synthetic integral image to be perceived even when bent, providing a secure and authentic verification method.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a planar optical arrangement with image data bearer structures and lenses is used, then a synthetic image can be generated on flat surfaces, but the image deteriorates when applied to curved surfaces
Solution Approach 1:
The patent applies the dynamics principle by making the optical system adaptable to different surface curvatures. The lens array and image data bearer structures are configured with specific spacing relationships that allow the system to maintain proper optical function when bent or curved, transforming a static planar system into a dynamically adaptable one that preserves image quality across varying surface geometries
Solution Approach 2:
The patent employs parameter changes by carefully controlling the spacing between lenses and image data bearer structures. By setting specific distance parameters (where the distance between the lens array and image data bearer structures equals the focal length of the lenses), the system can maintain optimal optical performance when applied to curved surfaces, effectively adapting the physical parameters to preserve image quality
2Ease of manufacture
If traditional security devices with synthetic images are used, then images can be displayed, but they lack unique structures that are easy to detect yet difficult to copy
Solution Approach 1:
The patent applies asymmetry by creating a specific geometric relationship where the array of image data bearer structures is intentionally misaligned relative to the lens array. This asymmetric configuration, combined with the specific spacing parameters, creates a unique optical signature that is easy to verify visually but extremely difficult to replicate accurately, thereby enhancing security reliability while maintaining ease of detection
Solution Approach 2:
The patent implements local quality by giving different regions of the optical structure distinct characteristics. The image data bearer structures contain specific patterns (such as text or symbols) that are locally optimized for detection, while the overall asymmetric arrangement provides global security. This local differentiation makes the security feature both detectable and hard to copy
3Reliability
If axial markings are created by irradiation through microspheres at the final product stage, then security images can be created, but mass production becomes very difficult and irradiation sensitive goods cannot be used
Solution Approach 1:
The patent applies preliminary action by pre-configuring the optical structures (lens array and image data bearer structures) during the manufacturing process rather than creating security features at the final product stage. The specific spacing and alignment relationships are established in advance, allowing mass production to proceed efficiently without requiring subsequent irradiation steps, thereby enabling both high productivity and security reliability
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
Enables high-quality synthetic images on non-planar surfaces and provides unique security features that are difficult to replicate, enhancing authentication and security applications.
Implementation Method 1
an array of microimages which, when viewed through a corresponding array of substantially spherical microlenses, generates a magnified image
Implementation Method 2
A second interface of the polymer foil stack has focusing elements in a second array
Implementation Method 3
This result is achieved according to the long known Moiré effect and was now applied to provide security labels with images having a three-dimensional appearance
Data Source
AI summary
An optical device for providing a synthetic integral image (25) comprises a polymer foil stack. A first interface of the polymer foil stack comprises optically distinguishable image data bearer structures (16A-C) in a first array. A second interface of the polymer foil stack has focusing elements (1) in a second array. A ratio between distances between neighboring objects in the first array and of focusing elements in the second array in a first direction is different from a ratio between distances between neighboring objects in the first array and of focusing elements in second array in a second direction. This leads to that the synthetic integral image corresponding to the image data bearer structures is perceptible with requested proportions when the polymer foil stack is given a certain curvature. Also polymer foil stacks giving rise to synthetic integral image only when viewed from a very short distance are described. The appearance of the synthetic integral image during bending or moving of the polymer foil stack is used for authentication. A change in apparent image depth during rotation is alternatively used for authentication.