Patent ID: 6104285
Filing Date: 2000-08-15
Classification: G06K,G08B

Abstract:
An anti-theft security system for securing merchandise comprising:a base station having a low frequency (LF) stage with a LF transmitting and receiving unit;an antenna attached to said base station said antenna for generating an electromagnetic field;a plurality of security labels for attachment to merchandise each having an active transponder, wherein each transponder comprises a LF stage having a LF transmitter and receiving unit operating on the same frequency as said base station LF stage, so that in response to a LF signal from said base station, a bidirectional signal transmission takes place between the base station and at least one of the security label transponders; andan antenna disposed on said transponder's LF-transmitting-and-receiving unit, wherein said antenna serves for both signal reception and transmission;a HF-transmitter for operating at high frequency and associated with said at least one security label transponder, which HF transmitter is prompted by said LF-transmitting and receiving unit; anda HF-receiving unit associated with said base station operating on the same frequency as said HF-transmitter of said transponder.