Authenticable Halftone Images via Luminescent Emissive Layer
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Solution Overview
Problem
Existing authentication methods for security documents and valuable items lack effective means to create secure, counterfeit-resistant images that change appearance under different lighting conditions, particularly failing to combine luminescent and non-luminescent layers for secure and accurate authentication.
Innovation Solution
The method involves creating a security device with a luminescent emissive layer on one side and a non-luminescent transmissive halftone layer on the other, using a separating transmissive layer, where the luminescent backlit image is formed by the emission of the emissive layer transmitted through the non-luminescent halftone layer, and the non-luminescent image is visible under normal light, with optional UV-absorbing layers for additional attenuation and security.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a luminescent emissive layer is combined with a non-luminescent transmissive halftone layer on opposite sides of a substrate, then authentication security is improved through appearance changes under different lighting conditions, but device complexity increases due to multiple layers and registration requirements
Solution Approach 1:
The authentication device is divided into two separate functional layers: a luminescent emissive layer on one side and a non-luminescent transmissive halftone layer on the opposite side. This segmentation allows each layer to perform its specific function independently while contributing to the overall authentication mechanism through their superposition.
Solution Approach 2:
The luminescent emissive layer and non-luminescent transmissive halftone layer are nested within a single substrate structure, with each layer positioned on opposite sides. The layers are optically coupled through the substrate, creating a compact integrated authentication device that combines multiple functional elements in a unified structure.
2Manufacturing precision
If high registration accuracy is required between front and back images for see-through devices, then image alignment is improved, but manufacturing precision requirements increase
Solution Approach 1:
The halftone pattern is applied locally to the non-luminescent transmissive layer, creating a spatially varying optical property that enables image formation. This local quality approach allows the authentication effect to be achieved through controlled optical modulation at specific locations rather than requiring uniform properties across the entire device.
Solution Approach 2:
The luminescent emissive layer creates an optical copy of the authentication image that is viewed through the non-luminescent transmissive halftone layer. This copying mechanism allows the authentication information to be reproduced optically without requiring direct physical alignment of corresponding features, reducing manufacturing complexity.
3Manufacturing precision
If the luminescent layer emission is attenuated by the non-luminescent halftone layer to create the backlit image, then image quality is improved through intensity and color variations, but light transmission is reduced
Solution Approach 1:
The optical properties of the non-luminescent transmissive halftone layer are carefully controlled to achieve optimal attenuation of the luminescent emission. By adjusting the halftone parameters, the device creates appropriate intensity and color variations in the backlit image while maintaining sufficient light transmission for effective authentication.
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 approach creates secure devices that are difficult to counterfeit, as both layers' intensities and colors are unknown, allowing for accurate authentication by comparing the images under normal and excitation light, ensuring the item's authenticity through unique appearance changes.
Implementation Method 1
a luminescent backlit image formed by a luminescent emissive layer on a verso side of a transmissive substrate illuminating a non-luminescent transmissive color halftone image on a recto side of the substrate
Implementation Method 2
The luminescent backlit image is formed by the emission of the emissive layer transmitted through the non-luminescent halftone layer
Implementation Method 3
the luminescent backlit image is formed by the emission of the emissive layer transmitted through the non-luminescent halftone layer
Data Source
AI summary
A method and computing system are proposed for producing an authenticable security device with two sides. The verso side is covered with an adjustable luminescent emissive layer formed by invisible luminescent ink halftones and possibly a UV absorbing printed layer. The recto side is covered with transmissive non-luminescent ink halftones. The backlit colors resulting from the emissions of the luminescent layer or resulting from illumination by normal white light through the transmissive non-luminescent ink halftones are predicted by a backlighting model. This model enables computing the surface coverages of the luminescent and/or non-luminescent ink halftones in order to obtain a desired color either under excitation light (UV light) or under normal white light. This enable creating authenticable backlit images substantially similar to pre-stored reference images, either under normal white light, under excitation light, or under both the normal white light and the excitation light.