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Theftproof device

  • US 4,639,713 A
  • Filed: 09/16/1982
  • Issued: 01/27/1987
  • Est. Priority Date: 09/18/1981
  • Status: Expired due to Term
First Claim
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1. A theftproof device comprising:

  • an elongate flexible tying member having two ends;

    an optical fiber longitudinally extending through said flexible tying member and having two ends, one end of said optical fiber being located at one end of said flexible tying member and another end of said optical fiber being located at the other end of said flexible tying member;

    said flexible tying member having a looped portion including said other end thereof;

    a light emission element arranged opposite one end of said optical fiber, for converting an electric signal supplied thereto into a corresponding photo signal;

    a light receiving element arranged opposite another end of said optical fiber, for converting a photo signal supplied thereto into a corresponding electric signal;

    at least one electric wire longitudinally extending through said flexible tying member adjacent said optical fiber, said electric wire being connected to a selected one of said light emission and light receiving elements for transmitting an electric signal transduced by the selected one of said elements, so that (i) when the electric wire is connected to the light emission element, the wire transmits an electric signal to be transduced to a photo signal by said light emission element, and (ii) when the electric wire is connected to the light receiving element, the wire transmits an electric signal which has been transduced from a photo signal by said light receiving element;

    a fixture adapted to be fixed to an object which is to be protected from theft,said flexible tying member being adapted to have said one end thereof passed through said looped portion after said flexible tying member is wound around a solid structure adjacent said object to be protected from theft;

    plug means provided at one end of said flexible tying member for mechanically connecting one end of said flexible tying member to said fixture, said plug means being adapted to disconnectably connect said one end of said flexible tying member to said fixture;

    a caulking member caulked to join said other end of said flexible tying member to an end part of said looped portion opposite said other end of said flexible tying member,said caulking member accomodating one of said light emission and light receiving elements;

    an electrical circuit arranged in said fixture for supplying an electric signal to said light emission element and also disposed to be supplied with an electric signal generated by said light receiving element; and

    connector means arranged within said plug means for electrically connecting said light emission element and said light receiving element to said electrical circuit, one of said light emission and light receiving elements being electrically connected to said connector means by way of said at least one electric wire;

    said electrical circuit operating in a manner such that upon occurrence of a change in a photo signal generated by said light emission element and transmitted through said optical fiber, caused by disconnection or cutting of either said optical fiber or said at least one electric wire, said electical circuit is operable in response to a change in an electric signal supplied thereto from said light receiving element, which corresponds to said change in said photo signal, to perform a predetermined warning function.

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