Smartphone-Verifiable Phosphor Security Feature
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing phosphor-based security features are difficult to verify using commercially available smartphones due to short decay times and high-intensity flash light interference, making it challenging to reliably detect luminescence signals.
Innovation Solution
A phosphor-based security feature with Ce3+ and Mn2+ co-doped silicate-garnet phosphors, such as Ca3Sc2Si3O12:Ce3+, Mn2+, which have decay times between 5 to 30 milliseconds, allowing for reliable detection of luminescence signals after flash excitation using a smartphone's camera, and are designed to emit in the visible spectral range, ensuring high spectral excitability and luminescence yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional phosphors with short decay times are used, then the security feature can be excited by smartphone flash, but the luminescence signal decays too quickly to be reliably detected
Solution Approach 1:
The patent changes the decay time parameter of the phosphor from conventional short decay times to specifically 5-30 milliseconds, which is slow enough to be captured by smartphone camera exposure times but still represents a defined temporal characteristic for verification
2Power
If high-intensity flash light is used for excitation, then the phosphor can be effectively excited, but the flash light interferes with detecting the luminescence signal
Solution Approach 1:
The patent uses the flash light to excite the phosphor in advance, then waits for the flash to cease before the camera captures the luminescence signal, utilizing the extended decay time to separate the excitation phase from the detection phase
Solution Approach 2:
The patent converts the potentially harmful flash light interference into a beneficial excitation source, using the same flash that causes interference to provide the necessary energy to excite the phosphor, then relying on the temporal separation provided by the extended decay time
3Ease of manufacture
If standard phosphors are used, then the security feature can be manufactured, but verification requires considerable technical effort and specialized equipment
Solution Approach 1:
The patent makes the smartphone serve multiple functions: it provides the excitation light through its flash, acts as the detection device through its camera, and performs the verification through its processor, eliminating the need for specialized verification equipment
Solution Approach 2:
The patent enables the smartphone to verify security features using its own built-in flash and camera components, making the verification process self-contained and eliminating dependency on external specialized equipment
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 secure and efficient verification of security features using commercially available smartphones, providing a high level of authenticity and integrity check without being visually perceivable, even after excitation.
Implementation Method 1
a phosphor that can be excited to luminescence by electromagnetic radiation of a predetermined wavelength
Implementation Method 2
The emission of the phosphor has a decay time in the millisecond range
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a smartphone-verifiable security feature (01) containing a luminescent material which can be excited to luminescence by visible electromagnetic radiation generated by a smartphone and, after termination of the excitation, exhibits an emission which can be detected by means of an image-capturing unit of the smartphone for a decay time in the range of 1 ms to 100 ms. The invention also relates to an assembly for verifying a security document (02) which comprises such a security feature (01).