Security Image Multiplexing via Laser Structured Metal Nanoparticles
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Solution Overview
Problem
Current methods for displaying multiple images on security documents are limited in the number of images and colors that can be shown, often requiring spatial filtering systems or modifications to the document structure, and typically result in black and white or binary images that are not easily distinguishable.
Innovation Solution
A method for multiplexing color images by selecting and combining color sets that can be displayed under different illumination and observation modes, using a marking technique such as laser structuring of metal nanoparticles, to optimize the number of distinct, colorful images that can be displayed without the need for spatial filtering systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If spatial filtering systems or document structure modifications are used to display multiple images, then the number of images that can be displayed increases, but the device complexity and manufacturing complexity increase
Solution Approach 1:
The patent changes the optical parameters of the security document by using materials with different refractive indices and optical properties. Multiple images are encoded by varying the optical parameters (refractive index, thickness, material composition) of different layers and structures, allowing images to be displayed under different illumination and observation conditions without requiring complex spatial filtering systems
Solution Approach 2:
The patent employs composite material structures consisting of multiple layers with different optical properties (e.g., polymer layers, metal oxide layers, nanocomposite materials). These composite structures enable multiple images to be displayed by exploiting the different optical responses of each material layer under various illumination and observation conditions, eliminating the need for complex observation systems
2Ease of manufacture
If conventional marking techniques are used to produce multiple images, then the manufacturing process is simple, but the images are limited to black and white or binary colors that are not easily distinguishable
Solution Approach 1:
The patent utilizes changes in optical parameters (refractive index, thickness, material composition) of the security document layers to generate different colors. By controlling these parameters during the marking process, full-color images with high distinguishability can be produced using relatively simple marking techniques, avoiding the need for complex multi-color printing processes
Solution Approach 2:
The patent employs materials and structures that exhibit color changes under different illumination and observation conditions. By encoding images using these color-changing properties, the security document can display multiple distinguishable color images without requiring complex coloring processes, maintaining ease of manufacture while significantly improving color differentiation
3Quantity of substance
If the security document structure is modified to display more images, then the number of images increases, but the manufacturing complexity and document complexity increase
Solution Approach 1:
The patent divides the security document into multiple functional layers, each with specific optical properties. Images are encoded by assigning different optical characteristics to different layers, allowing multiple images to be displayed through the combined optical response of these segmented layers. This segmentation enables complex image display functionality while maintaining relatively simple manufacturing of each individual layer
Solution Approach 2:
The patent designs the security document structure to serve multiple functions simultaneously: different layers and structures provide both aesthetic design elements and security verification features. The same optical structures that display multiple images also provide tamper evidence, authentication, and design functionality, reducing the need for separate components and simplifying the overall manufacturing process
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 the display of a larger number of different, colorful images on a security document, allowing for easy differentiation between them, without modifying the document structure or requiring complex observation systems, thereby enhancing security and authenticity.
Implementation Method 1
A method for multiplexing color images by selecting and combining color sets that can be displayed under different illumination and observation modes, using a marking technique such as laser structuring of metal nanoparticles
Data Source
AI summary
A method for building a security image for a security structure of a security document from multiplexing color images, including selecting a marking method capable of producing sets of colors on the security document comprising different colors that can be displayed according to illumination/observation modes of the security structure, establishing a plurality of color sets that can be displayed by the security structure in a plurality of the different illumination/observation modes, distributing the color sets in a plurality of groups of color sets, establishing combinations of groups of color sets having at least one color set in common across the number of different illumination/observation modes, selecting a combination of a group of color sets based on the number of desired illumination/observation modes and the number of colors per color image, and determining the color images to multiplex by means of the combination of the group of color sets selected.