Electronic article security system with digital signal processing and increased detection range

US5353011A · kind A · utility

Assignee

• CHECKPOINT SYSTEMS, INC. · US

Inventors

• Richard G. Wheeler · Belmont, US
• Burton S. Abrams · Whitemarsh, US
• Joseph M. Cannon · Harleysville, US
• Stephen J. Casey · Marlton, US
• Luke C. Chang · Deptford, US
• Von Ertwine · Langhorne, US
• Douglas Makofka · Willow Grove, US
• Louis Mastrocola · Blue Bell, US
• Calvin R. Waples, Jr. · Swedesboro, US

Key dates

• Filing date: Jan 4, 1993
• Grant date: Oct 4, 1994
• Expiry date: Jan 4, 2013

Classification

• Technology area (CPC G): Physics
• CPC primary: G08B13/2482
• WIPO field: Control
• WIPO sector: Instruments

Abstract

An improved electronic article security system is employed for detecting the presence of a security tag within a detection zone. The system includes a transmitter for generating electromagnetic energy and, in the disclosed embodiment, a single antenna for emitting electromagnetic energy received from the transmitter to establish an electromagnetic field within the detection zone and for sensing disturbances within the electromagnetic field, including disturbances resulting from a security tag within the detection zone. A receiver is provided for processing signals from the antenna relating to sensed disturbances and for providing output signals. A data processing and control section analyzes the output signals from the receiver and determines whether a sensed disturbance within the electromagnetic field is caused by the presence of a security tag within the detection zone. The output signals from the receiver are analyzed in accordance with predetermined criteria and pattern recognition techniques based upon receiver output signals which would be expected if a security tag were present in the detection zone to establish a security tag probability percentage.