EAS RFID Tag Deactivation via MOS Capacitor Breakdown
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Solution Overview
Problem
Existing deactivation systems for UHF electronic article surveillance (EAS) and radiofrequency identification (RFID) tags are ineffective in deactivating tags from a distance without direct contact, due to the high energy requirements of diodes used in these systems, leading to impractical and costly solutions with limited deactivation ranges.
Innovation Solution
Incorporating a low breakdown voltage capacitor, such as a metal-oxide-semiconductor (MOS) capacitor or a MOSFET with low breakdown characteristics into the EAS/RFID tag, allowing for deactivation at a distance through a low voltage or high voltage induced across the capacitor, which can be achieved without physical contact with the deactivation device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a diode is used in the EAS/RFID tag, then the tag can be deactivated by direct contact with a deactivation device, but the deactivation distance is limited and the system becomes impractical for remote deactivation
Solution Approach 1:
The patent changes the electrical parameter of the non-linear element by replacing the diode with a MOS capacitor that has a specifically designed low breakdown voltage (e.g., 5-20 volts). This parameter change allows the tag to be deactivated at much greater distances from the deactivation device, resolving the contradiction between reliable deactivation and limited deactivation distance.
2Length of moving object
If additional hardware devices such as switches are added to the deactivation system, then deactivation from a distance becomes possible, but the device complexity and cost increase significantly
Solution Approach 1:
The MOS capacitor in the tag automatically breaks down and deactivates the tag when exposed to a sufficiently strong electromagnetic field from the deactivation device. This self-service mechanism eliminates the need for additional deactivation hardware such as switches or control circuits, resolving the contradiction between extended deactivation distance and increased device complexity.
3Strength
If a robust diode is used in the tag, then the tag structure is stable, but substantial current is required for deactivation requiring direct contact
Solution Approach 1:
The patent changes the breakdown voltage parameter of the non-linear element from the high breakdown voltage characteristic of robust diodes to the low breakdown voltage characteristic of the MOS capacitor. This allows the tag to maintain structural stability while requiring only low voltage (and thus low energy) for deactivation, resolving the contradiction between structural strength and energy requirement.
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 reliable deactivation of combination EAS/RFID tags at considerable distances without additional hardware, improving deactivation efficiency and reducing costs by utilizing the non-linear behavior of the MOS capacitor to achieve irreversible breakdown and eliminate mixing signals.
Implementation Method 1
low breakdown voltage capacitor, such as a metal-oxide-semiconductor (MOS) capacitor or a MOSFET with low breakdown characteristics into the EAS/RFID tag, allowing for deactivation at a distance through a low voltage or high voltage induced across the capacitor, which can be achieved without physical contact with the deactivation device
Data Source
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AI summary
A combination Electronic Article Surveillance/Radio Frequency Identification ("EAS/RFID") tag and method and system for deactivating said combination EAS/RFID tags without the need to physically contact the tag with a deactivation device. The EAS/RFID tag replaces the conventional diode with a non-linear device such as a capacitor with a given breakdown voltage threshold. The introduction of a predetermined voltage across the capacitor results in destruction of the capacitor rendering the EAS/RFID tag undetectable in the interrogation systems.