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Chain-type door latch and alarm

  • US 4,233,595 A
  • Filed: 11/30/1978
  • Issued: 11/11/1980
  • Est. Priority Date: 11/30/1978
  • Status: Expired due to Term
First Claim
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1. A door latch and alarm apparatus comprising:

  • a door-mounted support;

    a doorjamb-mounted support;

    a relatively inextensible and flexible element anchored to said door support and having a free end provided with an end piece receivable in said doorjamb support;

    latch means including key-operable mechanism on said doorjamb support for releasably securing said end piece thereto, whereby the door can open a limited distance from the doorjamb before said element becomes taut and impedes further opening;

    circuit means including a pair of conductors extending between said door support and said end piece and a relatively fragile connector in said end piece forming a closed conductive path with said conductors, said connector being so much weaker than said element that when same is stressed beyond a certain limit said connector interrupts said path before said element breaks; and

    alarm means on said door-support connectable to said conductors for emitting an alarm when said path is interrupted.

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