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Unopened-door indicator

  • US 4,427,975 A
  • Filed: 04/29/1981
  • Issued: 01/24/1984
  • Est. Priority Date: 04/29/1981
  • Status: Expired due to Fees
First Claim
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1. An unopened-door indicator that shows the returning user of the indicator whether or not the door has been opened since the indicator was last enabled, and which comprises:

  • a. code input means;

    b. a door-actuated switch;

    c. an auxiliary output jack;

    d. an indicating light;

    e. electronic circuitry means responsive to a signal from said code input means when it is properly operated by the user, thereupon driving said indicating light to an un-opened door indication, providing a no-alarm signal to said auxiliary output jack, and providing a first delay of between 10 and 50 seconds before attaining an enabled state, thereupon becoming responsive to a signal from said door-actuated switch at the first opening of the door, thereupon becoming unresponsive to signals from said door-actuated switch, providing an alarm signal to said auxiliary output jack, and after a second delay of between 10 and 50 seconds, driving said indicating light to an opened-door indication; and

    f. power supply means for furnishing D.C. power to said code input means and said electronic circuitry means.

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