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System for monitoring the closing of a door

  • US 4,952,855 A
  • Filed: 11/15/1988
  • Issued: 08/28/1990
  • Est. Priority Date: 11/16/1987
  • Status: Expired due to Fees
First Claim
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1. A system for monitoring the closing state of a movable barrier which is mounted on a frame defining an opening and is movable between an open and a closed position, said system comprising:

  • first electric circuit means mounted on said barrier for being moved therewith and including first inductive means; and

    second electric circuit means mounted outside said barrier and including second inductive means and an oscillator means for producing, if switched on, an electric current in said second circuit means;

    said first and second inductive means being arranged with respect to each other in such a way that, if said oscillator means is switched on, said second inductive means is enabled to contactlessly induce electric energy in said first inductive means for activating said first electric circuit means, and said first inductive means is enabled to contactlessly induce an electric signal characteristic of a closure state of said barrier in second inductive means in at least one selected position of said barrier.

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