Antenna Coil Contactless Testing via Temporary Short-Circuit Bridge
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Solution Overview
Problem
Existing methods for testing the functionality of antenna coils in portable data carriers are complex, inaccurate, and unable to reliably detect faults, especially near the ends of the coil, and are not suitable for use during production without an integrated circuit.
Innovation Solution
A method involving the temporary short-circuiting of an open antenna coil to form a closed coil, allowing for contactless testing using impedance or resonant frequency analysis, and evaluating the free damped oscillation generated by an excitation pulse to detect defects such as conductor breaks or short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a direct current resistance measurement is used to test the antenna coil, then the ohmic component can be determined, but the frequency-dependent impedance and inductance cannot be determined
Solution Approach 1:
The patent changes the measurement parameter from direct current resistance to alternating current impedance measurement. By using an AC signal source and measuring the complex impedance (both resistive and reactive components), the method obtains complete electrical characteristics of the antenna coil including ohmic resistance, inductance, and frequency-dependent impedance, resolving the information loss problem while maintaining measurement accuracy.
2Reliability
If a phase and impedance analyzer is used for contactless testing, then the resonant frequency and quality can be determined, but the device complexity and test duration increase significantly
Solution Approach 1:
The patent replaces the complex mechanical/electrical phase and impedance analyzer with a simpler electromagnetic induction-based testing system. By using a testing coil that generates a magnetic field to induce current in the antenna coil, and detecting the induced voltage signal, the system achieves contactless fault detection with much simpler device architecture and faster operation suitable for production line integration.
3Measurement precision
If the antenna coil is tested in open form without short-circuiting, then faults far from the ends can be detected, but faults near the ends cannot be reliably detected
Solution Approach 1:
The patent applies a preliminary action by short-circuiting the ends of the open antenna coil before testing. This transformation converts the open coil into a closed loop, which enhances the magnetic coupling with the testing coil and improves the signal strength. As a result, faults near the ends of the original open coil become detectable through the modified closed configuration, while faults elsewhere remain detectable as well.
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 quick, easy, and cost-effective detection of faults in antenna coils, including those near the ends, during production, and differentiates between open and closed coils, allowing for reliable identification of defects and type of fault.
Implementation Method 1
a magnetic field is generated by a current pulse which induces a current in the antenna coil
Implementation Method 2
an electromagnetic signal is generated by the antenna coil which is picked up by a receiving coil
Data Source
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AI summary
In a method for testing the functionality of an antenna coil (20) for a contactless communicating portable data carrier, the functionality of a closed antenna coil (20) is tested in a first step. If the antenna coil (20) to be tested was originally an open antenna coil (20), the contactless testing step is preceded by a step of forming the closed antenna coil (20) by connecting the ends of the open antenna coil (20) by means of a short-circuit bridge. Subsequently, in a second step, a conductor track of the antenna coil (20) is interrupted to create an open antenna coil (20) before the antenna coil (20) is connected to components of an integrated circuit (30), in particular a chip.