Field generation and reception system for electronic article surveillance
Patent 5005001 Issued on April 2, 1991. Estimated Expiration Date: 
April 5, 2010. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
April 5, 2010. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent References 3747086 Pilferage detection systems Surveillance method and system with electromagnetic carrier and plural range limiting signals Apparatus and method for detecting a magnetic marker Multiple loop antenna Patent #: 4872018 InventorAssigneeApplicationNo. 505079 filed on 04/05/1990US Classes:340/551, Disturbance of magnetic field340/572.2Specified relationship between field and detection frequencies (e.g., nth order harmonics)ExaminersPrimary: Swann, III, Glen R.Assistant: Mullen, Thomas J. Jr. Attorney, Agent or FirmInternational ClassG08B 013/24AbstractAn electronic surveillance system includes a signal generator for generating a magnetic field, a signal receiver within the influence of the magnetic field, and a ferromagnetic marker adapted to pass in the field for detection. The signal received includes an arrangement for generating a non-rotating field at a first frequency, and a rotating field at a second frequency that is lower than the first frequency. | |
