Security Mark Authentication Using Photochromic Spectral Changes
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Solution Overview
Problem
Security marks containing photochromic compounds are only visible during light absorption and invisible during light cessation, lacking attention-grabbing properties and thus limited in security performance.
Innovation Solution
A method utilizing a combination of photochromic compounds with different characteristics to create a time-dependent change in absorption or reflection spectra for authentication, involving irradiation with excitation light and calibration based on temperature, along with optional fluorescence analysis for enhanced security.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single photochromic compound is used in the security mark, then the mark becomes visible during light absorption and invisible during light cessation, but the security performance is limited due to lack of attention-grabbing properties
Solution Approach 1:
The patent combines multiple photochromic compounds with different photochromic characteristics (different absorption spectra, color development rates, and quenching rates) into a single security ink formulation. This composite approach creates a security mark that exhibits complex, multi-stage color changes when irradiated with light, making it more visually distinctive and harder to replicate, thereby improving both security performance and visual attention-grabbing properties
Solution Approach 2:
The patent utilizes changes in multiple parameters of photochromic compounds simultaneously - including absorption wavelength, color development rate, and quenching rate - by selecting compounds with different characteristics. This multi-parameter approach allows the security mark to display different visual properties at different time points during irradiation, enhancing both security verification capability and visual impact
2Measurement precision
If multiple photochromic compounds with different characteristics are combined, then authentication accuracy is improved through time-dependent spectral changes, but the device complexity increases
Solution Approach 1:
The patent employs periodic irradiation with excitation light to induce sequential color development and quenching in the multiple photochromic compounds. By measuring the absorption or reflection spectrum at specific time intervals during this periodic irradiation cycle, the authentication system can capture the characteristic time-dependent spectral changes of the compound combination, achieving high authentication accuracy through temporal sampling rather than continuous complex monitoring
Solution Approach 2:
The patent creates a reference database storing the characteristic time-dependent spectral change patterns of authentic security marks containing specific combinations of photochromic compounds. During authentication, the measured spectral changes are compared against these pre-stored reference patterns, simplifying the authentication process to a pattern-matching operation rather than requiring complex real-time analysis of multiple parameters
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 enhances security performance by providing a visible authentication method that is distinguishable and secure, utilizing the unique spectral changes of multiple photochromic compounds to verify the authenticity of security marks.
Implementation Method 1
Photochromism refers to a phenomenon of some types of materials in a solid or solution state changing its color by absorption of light (ultraviolet or visible light) having a specific wavelength and retrieving the original color by absorption of light (ultraviolet or visible light) having another wavelength or by cessation of the absorption of light
Implementation Method 2
a process of irradiating a security mark containing a photochromic compound and a fluorescent compound with excitation light, a process of acquiring first security information on a time-dependent change in an absorption spectrum or a reflection spectrum of the security mark after the irradiation with the excitation light, and a process of acquiring second security information on a spectrum of fluorescence emitted from the security mark
Data Source
AI summary
A method for authenticating a security mark containing a photochromic compound can provide higher security performance. The method comprises a process of irradiating a security mark containing a photochromic compound with excitation light, a process of acquiring first security information on a time-dependent change in the absorption spectrum and/or reflection spectrum of the security mark after the irradiation with excitation light, and a process of checking the acquired first security information against previously acquired first security information on the security mark. In this method, the security mark preferably contains two or more photochromic compounds different from one another in color development and/or in quenching rate after the color development in a photochromic reaction.