Secure Tag Barrier Material Blocks UV Excitation
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Solution Overview
Problem
The use of low-cost ultra-violet radiation excitation sources for rare earth doped particles in secure tags can compromise their security, as it can stimulate all transitions, reducing the specificity and security of the tags.
Innovation Solution
Incorporating a barrier material with high absorption coefficients for low-wavelength radiation, such as titanium dioxide or polyimide, to shield rare earth ions, ensuring that only higher wavelength excitation sources can stimulate specific transitions, thereby enhancing security.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If low-cost ultra-violet radiation excitation sources are used to stimulate all transitions in rare earth doped particles, then the ease of operation and cost are improved, but the security and specificity of the tags deteriorate
Solution Approach 1:
A barrier material layer is introduced as an intermediary between the excitation source and the rare earth doped particles. This barrier layer selectively transmits only specific wavelength ranges (e.g., 400-700nm visible light) while blocking other wavelengths (e.g., UV below 400nm), thereby mediating the interaction between the excitation source and the secure tag particles to prevent unauthorized excitation of all transitions
Solution Approach 2:
The excitation wavelength parameter is changed and restricted from broad-spectrum UV radiation to specific visible light wavelengths (400-700nm). By using a barrier material that only transmits this specific wavelength range, the system changes the excitation parameter from low-cost UV to more specific visible light, thereby improving security while maintaining operational feasibility
2Adaptability or versatility
If high frequency broadband excitation sources are used to stimulate all transitions in rare earth ions, then the versatility and ease of operation are improved, but the measurement precision and security deteriorate
Solution Approach 1:
The barrier material acts as a wavelength-selective intermediary that filters the broadband excitation source, allowing only specific wavelength ranges to reach the rare earth doped particles. This mediation ensures that only intended transitions are stimulated, improving measurement precision and security while maintaining the ability to use versatile excitation sources
3Measurement precision
If narrowband tuned excitation sources are used to optimize luminescence from specific transitions, then the measurement precision and security are improved, but the device complexity and ease of operation worsen
Solution Approach 1:
Instead of using complex narrowband tuned excitation sources, the patent uses a simple barrier material intermediary that passively filters wavelengths. This approach achieves the same security and specificity goals as complex tuned sources but with much simpler device architecture, avoiding the need for complex wavelength-tuning mechanisms
Solution Approach 2:
The barrier material provides a simple, low-cost, passive filtering solution that replaces expensive and complex narrowband excitation sources. The barrier layer is a straightforward optical filter that achieves wavelength selection without requiring complex active control or tuning mechanisms
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 barrier material prevents low-wavelength radiation from exciting the secure tags, necessitating a higher wavelength excitation source, increasing the security and specificity of the luminescence response, making the tags more secure against counterfeiting.
Implementation Method 1
the barrier material may have a high coefficient of absorption for radiation between 10nm and 400nm, particularly for radiation between 300nm and 400nm
Implementation Method 2
the barrier material may be in the form of a highly reflective and/or scattering material, such as titanium dioxide or zinc oxide
Implementation Method 3
In response to suitable excitation, RE particles produce a luminescence spectrum having narrow peaks because of the atomic (rather than molecular) transitions involved
Implementation Method 4
a suitable excitation source to stimulate transitions in the secure tag, and (ii) a detector to measure the luminescence emitted in response to the excitation
Data Source
Figure 1
AI summary
A secure tag (30) comprising: a carrier doped with one or more rare earth ions, and a barrier material (28) associated with the carrier and substantially blocking low-wave length radiation to shield the rare earth ions from low-wave length radiation. This enables a secure tag to be fabricated that does not photoluminesce strongly in response to a low-wavelength excitation radiation source.