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Lock and alarm apparatus

  • US 4,151,506 A
  • Filed: 09/20/1976
  • Issued: 04/24/1979
  • Est. Priority Date: 09/20/1976
  • Status: Expired due to Term
First Claim
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1. Alarm apparatus comprising a housing, said housing including means forming an access opening to the interior thereof, and further including a closure for said access opening, fastener means for securing said closure to said housing, said fastener means comprising at least one electrically conductive securing member, and a corresponding mounting member which is connected to said housing and to which said securing member is affixed in said secured position of said closure, said mounting member being formed of dielectric material and having a pair of spaced apart electrically conductive elements disposed therein that are electrically connected only when said securing member is in engagement with both of said elements, a power source, a connector element having a pair of ends and being formed at least partially of an electrically conductive material extending substantially over the entire length thereof, insulating means substantially surrounding said electrically conductive material, means for securing said ends of said connector element to said housing, warning signal means operable when electrically connected to said power source to emit a warning signal, control circuitry connected to said electrically conductive material and operable to provide for the operation of said warning signal means for a preset length of time in response to an electrically conductive contact with said conductive material, said control circuitry comprising detecting means having input means connected to said conductive material, resettable triggering means connected to said detecting means, actuating means connected to said triggering means, said actuating means including timer means and being operable when activated to connect said warning signal means to said power source for said preset length of time, means for supplying a voltage to said input means, said detecting means providing a signal to said triggering means to initiate said actuating means to connect said warning signal means to said power source for said preset length of time in reponse to a preselected voltage variance from said voltage at said input means, said connector element and said control circuitry being connected so that said voltage is varied at said input means in response to an electrically conductive contact with said electrically conductive material thereby effecting a conductive path to said input means, and tamper circuitry operable to connect said warning signal means to said power source, said securing member and said elements forming an electrical path in said tamper circuitry in the secured position of said closure to said housing, said electrical path being interrupted in response to disengagement of said securing member with one of said elements thereby providing for the connection of said power source to said warning signal means to generate said warning signal.

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