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Proximity detector

  • US 4,208,695 A
  • Filed: 03/24/1978
  • Issued: 06/17/1980
  • Est. Priority Date: 03/24/1977
  • Status: Expired due to Term
First Claim
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1. A proximity detector comprising;

  • a pair of antennae being disposed along the front edge of a door and at a space therebetween;

    a pair of coils constituting series resonance circuits, together with earth electrostatic capacities of said antennae which are connected in series with said coils;

    an AC power source for supplying voltages to said series resonance circuits;

    rectifying circuits for rectifying the voltages produced in said antennae by said AC power source; and

    differential amplifier circuit for amplifying difference between the outputs of said rectifying circuits, the output of said differential amplifier controlling the movement of said door.

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