MOS Capacitor EAS Tag Remote Deactivation via Voltage Breakdown
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Solution Overview
Problem
Existing UHF electronic article surveillance (EAS) systems face limitations in deactivating tags from a distance without direct contact, as they require substantial current to destroy diode-based tags, making them impractical and costly, especially when additional deactivation elements are needed to achieve low deactivation distances.
Innovation Solution
Incorporating a non-linear Metal-Oxide-Semiconductor (MOS) device with low breakdown voltage into the EAS tag, which exhibits non-linear capacitance below a threshold and linear capacitance above it, allowing for deactivation by applying a predetermined voltage that breaks down the insulation layer, enabling remote deactivation without additional hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If diode-based tags are used in UHF EAS systems, then the tags can be deactivated by direct contact with deactivation devices, but the deactivation device must be in direct contact with the tag and requires substantial current, making it impractical for remote deactivation
Solution Approach 1:
The patent changes the electrical parameters of the tag by replacing the diode with a MOSFET device that has a gate structure. This allows the tag to respond to voltage changes rather than requiring substantial current, enabling remote deactivation through voltage induction from the deactivation device without direct contact.
Solution Approach 2:
The patent replaces the mechanical contact-based deactivation system with a field-based system. Instead of requiring physical contact between the deactivation device and tag, the system uses electromagnetic field induction to transfer energy to the MOSFET gate, achieving deactivation at a distance.
2Ease of operation
If additional hardware devices such as switches are added to the deactivation system to avoid direct contact, then remote deactivation becomes possible, but the system becomes costly and cumbersome with relatively low deactivation distances
Solution Approach 1:
The MOSFET device serves multiple functions: it acts as the non-linear element for signal detection during normal operation and as the deactivation mechanism when voltage is applied to the gate. This eliminates the need for separate switches or additional deactivation hardware, reducing system complexity while enabling remote deactivation.
Solution Approach 2:
The tag's own MOSFET structure provides the deactivation mechanism. The gate of the MOSFET, which is already part of the tag's circuitry, serves as the interface for receiving deactivation signals. The tag uses its existing components to achieve deactivation without requiring external added elements.
3Reliability
If diodes are used in EAS tags, then the tags exhibit predictable non-linear behavior, but the breakdown characteristics require substantial current, rendering remote deactivation ineffective
Solution Approach 1:
The patent changes the electrical parameters by using a MOSFET instead of a diode. The MOSFET exhibits non-linear current-voltage characteristics similar to diodes for detection purposes, but its gate structure allows it to respond to voltage changes with minimal current, enabling remote deactivation while maintaining predictable behavior.
Solution Approach 2:
The MOSFET device separates the detection function (performed by the channel between source and drain) from the deactivation function (performed by the gate). This segmentation allows the tag to maintain predictable non-linear behavior for detection while enabling low-current voltage-based deactivation through the gate.
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 MOS device allows for reliable deactivation of EAS tags at considerable distances without direct contact, improving detection performance and reducing costs by eliminating the need for additional deactivation elements, while maintaining effective deactivation capabilities.
Implementation Method 1
The nonlinear component exhibits non-linear capacitance with respect to voltage below a breakdown voltage threshold and exhibits a linear capacitance with respect to voltage above the breakdown voltage threshold
Implementation Method 2
The tag includes an antenna circuit
Data Source
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Figure 3~4
AI summary
An Electronic Article Surveillance ("EAS") tag and method and system for deactivating EAS tags without the need to physically contact the tag with a deactivation device. The EAS tag replaces the conventional diode with a non-linear device such as a metal-oxide-semiconductor ("MOS") capacitor with a given breakdown voltage threshold. Inducing a predetermined voltage across the MOS capacitor results in destruction of the MOS capacitor rendering the EAS tag undetectable in the EAS interrogation system.