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Detection device having energy transmitters located at vertically spaced apart points along movable doors

  • US RE33,668 E
  • Filed: 03/22/1990
  • Issued: 08/20/1991
  • Est. Priority Date: 02/10/1981
  • Status: Expired due to Term
First Claim
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1. A method for detecting the presence of an object in the path of a closing sliding door, characterized by:

  • sequentially activating energy transmitters as the door closes, to transmit energy .[.between.]. .Iadd.from .Iaddend.vertically spaced apart points along one of the two vertical edges of the area closed by the door to a detector on the second of said edges, an imaginary line between the detector and each transmitter decreasing as the door closes and being at an angle greater than 0 but less than 90 degrees to the direction in which the door slides;

    sensing the transmitted energy with the detector for producing an output signal in response to the energy;

    sensing the output from the detector when the energy is transmitted from each energy transmitter and providing a door stop signal when there is no output from the detector when each energy transmitter is activated.

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