High-Frequency Resonant Circuit for Security Document Authentication
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Solution Overview
Problem
Existing authentication devices for value and security documents are not adequately compact or reliable, requiring increased installation space and operational safety concerns.
Innovation Solution
A device utilizing a high-frequency resonant circuit to generate an excitation field with reduced voltage amplitude, incorporating a transformer and electrode arrangement that minimizes space requirements while ensuring reliable operation, and optionally includes additional excitation methods for various security features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional excitation frequencies (few kHz) and high voltage amplitudes (>5 kV) are used to excite electroluminescent pigments, then the pigments can be effectively excited, but the device requires large installation space and air breakdown occurs more readily
Solution Approach 1:
The patent applies parameter changes by increasing the excitation frequency from conventional few kHz to high-frequency range (≥80 kHz), which enables the use of lower voltage amplitudes while still effectively exciting electroluminescent pigments. This parameter transformation resolves the contradiction by allowing compact device design without compromising excitation effectiveness or operational reliability.
Solution Approach 2:
The patent utilizes resonant oscillation at high frequencies to excite the electroluminescent pigments. By operating at the resonant frequency of the excitation circuit (≥80 kHz), the system achieves efficient energy transfer and pigment excitation with reduced voltage requirements, thereby enabling compact device architecture while maintaining reliable operation.
2Reliability
If high voltage amplitudes (>5 kV) are used to bridge air gaps and excite electroluminescent pigments, then excitation is achieved, but air breakdown occurs and safety concerns arise
Solution Approach 1:
The patent transforms the excitation parameters by operating at high frequencies (≥80 kHz) instead of conventional low frequencies. This parameter change enables the air gap to be bridged with significantly lower voltage amplitudes, preventing air breakdown and eliminating the associated safety hazards while maintaining effective pigment excitation.
Solution Approach 2:
The patent replaces the conventional low-frequency high-voltage excitation mechanism with a high-frequency resonant excitation mechanism. This substitution fundamentally changes the physical approach to bridging air gaps, using rapid oscillating fields that can penetrate air gaps without causing breakdown, thereby eliminating the harmful effect while achieving the same excitation goal.
3Reliability
If conventional excitation methods are used, then electroluminescent pigments can be excited, but the device complexity and installation space increase
Solution Approach 1:
The patent simplifies device structure by changing the excitation frequency parameter to high-frequency range (≥80 kHz). This parameter change enables the use of compact resonant circuits with smaller transformers and capacitors, reducing overall device complexity and installation space while maintaining effective pigment excitation through resonant coupling.
Solution Approach 2:
The patent employs a nested structure where the electroluminescent pigment is integrated within or on the security document, and the excitation electrodes are arranged to create a compact field distribution. This nesting approach minimizes the spatial requirements of the excitation system, reducing device complexity while ensuring effective excitation coverage.
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 reduces installation space and enhances operational reliability by using a high-frequency resonant circuit to efficiently excite electroluminescent pigments with lower voltage amplitudes, minimizing air breakdown risks and energy storage, thus enabling compact and safe authentication device designs.
Implementation Method 1
electroluminescent pigments, which light up when stimulated by a special sensor
Implementation Method 2
a resonant frequency of the oscillating resonance circuit is greater than or equal to 80 kHz
Implementation Method 3
The output voltage can be transformed into an excitation voltage with a second amplitude by means of the transformer
Implementation Method 4
a capacitance of the first electrode, wherein a resonant frequency of a resonant circuit, which includes at least one secondary inductance of the transformer and the capacitance of the first electrode
Data Source
Figure 1
AI summary
The invention relates to a method and a device for verifying the authenticity of a document of value or security document, in which said device (1) comprises at least one first alternating voltage source, one first transformer (3a), and at least one first electrode (4a), and in which said first transformer (3a) is electrically connected to the first alternating voltage source on the input side and to the first electrode (4a) on the output side. An output voltage with a first amplitude and an excitation frequency can be generated by means of the first alternating voltage source, the output voltage can be transformed by means of the first transformer (3a) into an excitation voltage with a second amplitude, the first electrode (3a) generates an electric excitation field as a function of this excitation voltage, and the first transformer (3a) and first electrode (4a) are designed such that a resonant frequency of a resonant circuit, which comprises at least one secondary inductor of the first transformer (3a) and a capacitor of the first electrode (4a), is greater than or equal to 80 kHz.