EAS System Synchronization via Local AC Zero Crossing Backup
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Solution Overview
Problem
Existing networked Electronic Article Surveillance (EAS) systems face synchronization issues when the synchronization signal from a Wireless Device Manager (WDM) is compromised, leading to poor pick performance or false alarms, as the zero crossing of the wirelessly transmitted signal can differ significantly from the local AC zero crossing at the end device.
Innovation Solution
The EAS system continuously compares the wirelessly transmitted zero crossing signal with the local AC source zero crossing, tracking a delta value to synchronize operations when the WDM signal is lost, allowing the end device to default to the local AC zero crossing plus/minus the correction factor derived from the previous WDM signal, ensuring continuous operation and re-switching back when the WDM signal is restored.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the EAS system uses the wirelessly transmitted synchronization signal from the WDM, then the system can operate in a networked fashion with centralized control, but the synchronization accuracy deteriorates when the WDM signal is compromised or lost
Solution Approach 1:
The patent introduces a dual-synchronization mechanism where the local AC zero crossing acts as a backup intermediary when the WDM signal is compromised. The system continuously compares the WDM transmitted zero crossing with the local AC zero crossing to detect and correct synchronization drift, ensuring reliable operation even when the primary networked synchronization source is unavailable.
Solution Approach 2:
The system performs beforehand cushioning by continuously monitoring and comparing synchronization signals from both the WDM and local AC source. When the WDM signal is lost or compromised, the system has already prepared the local AC zero crossing as a backup synchronization source, preventing synchronization failure and maintaining reliable EAS operation.
2Duration of action of stationary object
If the EAS system switches to the local AC zero crossing when the WDM signal is lost, then the system maintains continuous operation, but the pick performance deteriorates due to phase delays from transformer loading effects
Solution Approach 1:
The patent implements feedback by continuously comparing the WDM transmitted zero crossing timing with the local AC zero crossing timing. This feedback mechanism allows the system to detect phase delays caused by transformer loading effects and adjust the synchronization timing accordingly. When the WDM signal is available, the system uses the feedback to correct local AC timing deviations, maintaining high pick performance while ensuring continuous operation.
Data Source
AI summary
Systems and methods for operating an Electronic Article Surveillance (“EAS”) system. The method comprising: receiving, by an electronic device, a synchronization signal transmitted from a remote Wireless Device Manager (“WDM”); performing first transmit and receive operations at the electronic device that are synchronized in accordance with the remote WDM's AC power line zero crossing specified by the synchronization signal; detecting when the synchronization signal is no longer being received by the electronic device; and performing second transmit and receive operations at the electronic device that are synchronized in accordance with the electronic device's local AC power line zero crossing, when the synchronization signal has not been received by the electronic device for a specified period of time.