Luminescent Security Feature Using Phase Shift Detection
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Solution Overview
Problem
Current security features are inadequate in distinguishing between original and counterfeit products, especially at the individual item level, and existing luminescent security features are not effectively readable without technical tools.
Innovation Solution
A security feature using luminescent surface elements with varying lifetimes, allowing binary coding and encoding information, where the luminescence lifetime of each element differs, enabling identification without being readable with the naked eye, and a verification method using intensity-modulated excitation light and a lock-in imager to determine phase shifts for authentication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If luminescent materials with different lifetimes are used to encode information, then identification precision at individual item level is improved, but reading complexity increases requiring specialized equipment
Solution Approach 1:
The patent applies parameter changes by utilizing the luminescence lifetime parameter of fluorescent materials to encode information. Different luminescence lifetimes (e.g., 4ns, 8ns, 12ns) represent different binary values, enabling precise identification at the individual item level. This transforms a physical parameter (lifetime) into an information carrier, resolving the contradiction between identification precision and reading complexity.
Solution Approach 2:
The patent replaces traditional visual or manual inspection methods with optical measurement technology. By using a reading device that detects luminescence lifetime parameters through photodetectors and timing circuits, the system automates the identification process. This substitution of mechanical/visual methods with optical-electronic measurement resolves the reading complexity issue while maintaining high identification precision.
2Reliability
If security features are made invisible to the unaided eye, then security reliability is improved, but detectability worsens requiring technical tools
Solution Approach 1:
The patent applies local quality by making the security feature invisible under normal viewing conditions (to the unaided eye) while maintaining specific local properties (luminescence lifetime) that can be detected by specialized equipment. The fluorescent inks appear identical to the naked eye but exhibit distinct lifetime characteristics under UV excitation, enabling reliable authentication without compromising security.
Solution Approach 2:
The patent introduces an intermediary detection device that bridges the gap between invisible security features and human verification. The reading device with UV light source, photodetectors, and timing circuits acts as an intermediary that translates the invisible luminescence lifetime parameters into detectable signals, resolving the contradiction between security reliability and ease of detection.
3Loss of information
If complex encoding schemes are implemented, then information capacity increases, but manufacturing complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the security feature into multiple surface elements, each containing fluorescent ink with a specific luminescence lifetime. Information is encoded by assigning different lifetime values (4ns, 8ns, 12ns) to different surface elements or regions, creating a binary or multi-level code. This segmentation approach enables high information capacity while maintaining relatively simple manufacturing processes.
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 identification and verification of products at the serial or individual item level, providing a robust anti-counterfeiting solution that is cost-effective and easy to handle, while appearing unchanged to the unaided eye.
Implementation Method 1
A security feature is used which has a plurality of luminescent surface elements 31, 32, 33, 34, wherein a luminescence lifetime can be determined for each of these surface elements 31, 32, 33, 34 and the luminescence lifetime varies between the surface elements 31, 32, 33, 34
Implementation Method 2
the luminescence lifetime of the at least first feature material is determined, wherein first excitation light of a suitable frequency is emitted from an intensity-modulated light source 4 and causes the at least one feature material to exhibit modulated luminescence with a phase shift relative to the excitation light
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
A security feature (2) has a plurality of luminescent surface elements (31, 32, 33), the luminescence lifetime of which varies between the surface elements. To verify the security feature, a lock-in imager is used. The security feature is illuminated with excitation light (E(t)) that is intensity-modulated at a modulation frequency. The luminescence light (F(t)) emitted by the security feature is detected synchronously with the modulation frequency in a plurality of pixels (81). From this, a measure (S(Φ)) for a phase shift (Φ) between the excitation light and the luminescence light in different pixels (81) is determined. The security feature is then verified taking this measure for the phase shift in different pixels into account.