Deactivating device
First Claim
1. A deactivating device for deactivating shoplifting detection labels of an electronic shoplifting detection system, which labels comprise a resonant circuit with a coil and a capacitor, said deactivating device comprising an antenna circuit comprising an antenna coil tuned with at least one capacitor to the resonant frequency of the resonant circuit, by means of which sufficient energy can be induced in a resonant circuit of a label to effect electrical breakdown in the capacitor thereof, wherein the antenna coil of the deactivating device is coupled between a supply source and earth via a switching means having a conductive state and a blocking state;
- and control means for supplying at intervals control pulses to the switching means in order to bring the switching means into the conductive state;
wherein the energy necessary for deactivation is stored as magnetic energy in the antenna coil and the duration of each control pulse is chosen such that at the end of a control pulse, when the switching means returns to the blocking state, the energy necessary for deactivation has accumulated as magnetic energy in the antenna coil, which energy is subsequently converted into an alternating electromagnetic field for application to a detection label when the switching means is in the blocking state.
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Accused Products
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.
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Citations
22 Claims
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1. A deactivating device for deactivating shoplifting detection labels of an electronic shoplifting detection system, which labels comprise a resonant circuit with a coil and a capacitor, said deactivating device comprising an antenna circuit comprising an antenna coil tuned with at least one capacitor to the resonant frequency of the resonant circuit, by means of which sufficient energy can be induced in a resonant circuit of a label to effect electrical breakdown in the capacitor thereof, wherein the antenna coil of the deactivating device is coupled between a supply source and earth via a switching means having a conductive state and a blocking state;
- and control means for supplying at intervals control pulses to the switching means in order to bring the switching means into the conductive state;
wherein the energy necessary for deactivation is stored as magnetic energy in the antenna coil and the duration of each control pulse is chosen such that at the end of a control pulse, when the switching means returns to the blocking state, the energy necessary for deactivation has accumulated as magnetic energy in the antenna coil, which energy is subsequently converted into an alternating electromagnetic field for application to a detection label when the switching means is in the blocking state. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
- and control means for supplying at intervals control pulses to the switching means in order to bring the switching means into the conductive state;
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16. A deactivating device for deactivating shoplifting detection labels of an electronic shoplifting detection system, which labels comprise a resonant circuit with a coil and a capacitor, said deactivating device comprising an antenna circuit comprising an antenna coil tuned with at least one capacitor to the resonant frequency of the resonant circuit, by means of which sufficient energy can be induced in a resonant circuit of a label to effect electrical breakdown in the capacitor thereof, wherein the antenna coil of the deactivating device is coupled between a supply source and earth via a switching means having a conductive state and a blocking state;
- and control means for supplying at intervals control pulses to the switching means in order to bring the switching means into the conductive state;
wherein the energy necessary for deactivation is stored as magnetic energy in the antenna coil, and the duration of each control pulse is chosen such that at the end of a control pulse, when the switching means returns to the blocking state, the energy necessary for deactivation has accumulated as magnetic energy in the antenna coil, which energy is subsequently converted into an alternating electromagnetic field when the switching means is in the blocking state;
wherein the deactivating device comprises an auxiliary coil and an auxiliary capacitor, in which auxiliary energy is stored after the switching means has been brought into the conductive state, the auxiliary coil and capacitor supplying energy to the antenna circuit shortly after the energy conversion to the alternating electromagnetic field; and
wherein connected parallel with the switching means is at least one further capacitor, which at least one further capacitor is a voltage-dependent capacitor. - View Dependent Claims (17, 18, 19, 20, 21)
- and control means for supplying at intervals control pulses to the switching means in order to bring the switching means into the conductive state;
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22. A packagaing table for a shoplifting detecting system, which packaging table comprises a packaging table detector with a substantially rectangular antenna loop with branches extending diagonally, wherein a second substantially rectangular antenna loop which is of a shape similar to the first substantially rectangular antenna loop and arranged concentrically relative thereto is provided, which second antenna loop is part of a deactivating device for shoplift-detection labels.
Specification