Cube Corner Retroreflective Sheeting with Optically Variable Security Marks
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Solution Overview
Problem
There is a need to prevent unauthorized replication of security marks, such as those used in license plates, while ensuring they are visible to the unaided eye from a distance, leveraging the asymmetrical properties of prismatic retroreflective sheeting.
Innovation Solution
The use of optically variable marks in cube corner retroreflective sheeting, created through controlled irradiation patterns, which change appearance with observation and entrance angles, providing secure and visible features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optically variable marks are created in cube corner retroreflective sheeting through controlled irradiation patterns, then security against unauthorized replication is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by incorporating the optically variable mark directly into the cube corner retroreflective sheeting during the manufacturing process. The mark is formed by controlling the irradiation of radiation-curable resin in specific patterns before the sheeting is completed, embedding the security feature into the structure itself rather than adding it as a separate post-manufacturing step.
Solution Approach 2:
The patent utilizes parameter changes by varying the irradiation parameters (energy density, pattern, distribution) of radiation-curable resin during manufacturing. By controlling these parameters, different optical properties are created within the cube corner elements, producing the optically variable mark that changes appearance with viewing angle while maintaining retroreflective functionality.
2Illumination intensity
If optically variable marks are made visible to the unaided eye from a distance, then visibility and security are improved, but the difficulty of detecting and measuring the mark's properties increases
Solution Approach 1:
The patent applies local quality by creating specific regions within the cube corner retroreflective sheeting that have different optical properties. The optically variable mark consists of areas with varying irradiation patterns that create distinct visual characteristics at specific locations, allowing the mark to be visible and distinguishable from the surrounding retroreflective material when viewed from a distance.
Solution Approach 2:
The patent utilizes asymmetry through the optically variable mark that exhibits different visual properties at different viewing angles. The mark is designed to be non-symmetric in its optical response, creating an appearance that changes with observation angle, which enhances security by making the mark difficult to replicate while ensuring it is visible to the unaided eye when viewed from intended 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 solution effectively creates secure, tamper-proof images that are visible from specific angles, making them difficult to replicate and ensuring visibility when intended, suitable for security documents and signage.
Implementation Method 1
exposing the radiation curable resin to a first, patterned irradiation to provide a first energy density level of irradiation to the radiation curable resin in a first area of the plurality of cube corner cavities, to form a first optically variable mark element
Implementation Method 2
Retroreflective materials have the ability to redirect light incident on the material back toward the originating light source
Data Source
AI summary
Retroreflective sheeting having a structured layer of cube corner elements and an at least one optically variable mark therein, and methods of making same.