The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 19, 1993
Filed:
Sep. 30, 1991
Paulus Rebers, Groenlo, NL;
Tallienco W Fockens, Eibergen, NL;
N.V. Nederlandsche Apparatenfabriek Nedap, De Groenlo, NL;
Abstract
This invention relates to a deactivating device for deactivating shoplifting detection labels of an electronic shoplifting detection system. These labels comprise a resonant circuit with a coil and a capacitor and the deactivating device comprises an antenna circuit comprising an antenna coil tuned with at least one capacitor to the resonant frequency of the resonant circuit. By means of this arrangement, sufficient energy can be induced in a resonant circuit of a label to effect electrical breakdown in the capacitor thereof. According to the invention, the antenna coil of the deactivating device is coupled, on the one hand, to a supply source and, on the other, to earth via a switch. Circuitry is provided for supplying at intervals control pulses to the switch in order to bring the switch into the conductive state. The duration of each control pulse is chosen such that at the end of a control pulse, when the switch returns to the blocking state, the energy necessary for deactivation is stored as magnetic energy in the antenna coil. This energy is subsequently converted into an electromagnetic oscillation when the switch is in the blocking state.