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Method and device for sensing, identifying and protecting goods, particularly from theft

  • US 5,838,234 A
  • Filed: 08/27/1996
  • Issued: 11/17/1998
  • Est. Priority Date: 12/28/1994
  • Status: Expired due to Fees
First Claim
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1. A system for sensing, identifying and protecting goods against theft, comprising:

  • at least one local unit placed in an appropriate place in a controlled area, comprising;

    (i) a local receiver having a long range for receiving messages transmitted by a transmitter circuit located anywhere in said controlled area, and comprising means for transmitting the received alarm messages to a central processing unit, and(ii) a local transmitter having a short range for transmitting permanently an activating signal in a narrow transit area in the controlled area; and

    autonomous tags of at least a first and a second type, respectively fitted with objects to be protected in said controlled area, each tag comprising;

    (i) an electric power source,(ii) a transmitter circuit connected to said power source via a controlled switch, said transmitter circuit when powered by said power source transmitting an alarm message containing an identification signal to said local receiver when said tag is placed in said controlled area,(iii) a sensor for sensing a parameter representative of an unauthorized use of the object fitted with the tag,(iv) a receiver circuit for receiving said activating signal when said tag is placed in said transit area, and(v) a logic control circuit connected to said power source, said transmitter and receiver circuits, said controlled switch and said sensor, for controlling said controlled switch and for switching the tag from a disabled state to an enabled state when said sensor detects said parameter, the logic control circuit of the tags of said first type comprising means for switching the transmitter on to transmit an alarm message if both said tag is in said enabled state and said receiver circuit receives said activating signal from said local transmitter, the logic control circuit of the tags of said second type comprising means for switching the transmitter on to transmit an alarm message if said tag is in said enabled state.

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