Store alarms work by detecting special anti-theft tags attached to merchandise using magnetic fields.
Store security systems, often seen at entryways, utilize a simple yet effective technology to deter theft. At their core, these systems rely on a magnetic field and small, detectable tags placed on items.
The Science Behind Store Security Alarms
The fundamental principle involves creating a detection zone that reacts to active anti-theft tags.
Components of the System
The main components you see are:
- Doorway Sensors: These are the panels or pedestals located at the entrance/exit of the store.
- Anti-Theft Tags: Small, disposable or reusable tags attached to products.
The Detection Process
The process begins with the doorway sensors:
- Magnetic Field: In stores, there are sensors on the doorway that transmit and receive a weak magnetic field.
- Tag Entry: When an active anti-theft tag (meaning it hasn't been demagnetized or deactivated) enters this zone, it interacts with the magnetic field.
- Oscillation: This interaction causes oscillation within the tag.
- Signal Detection: The sensor will read the changes in the magnetic waves caused by the tag's oscillation.
- Alarm Activation: Detecting these specific changes triggers the system, causing an alarm to go off.
This sequence ensures that if an item with an active tag is carried through the detection zone, the system immediately alerts staff.
Active vs. Deactivated Tags
The key to preventing the alarm from sounding during a legitimate purchase is the tag's state:
- Active Tag: A tag that has not been demagnetized or deactivated. It will interact with the magnetic field and trigger the alarm.
- Deactivated Tag: During the checkout process, the tag is either physically removed or electronically demagnetized using a special pad or scanner. A deactivated tag will not cause oscillation and will pass through the magnetic field zone without triggering the alarm.
This distinction allows stores to secure merchandise while permitting paying customers to leave without incident after the tag is neutralized.
