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Automatic assist for swing-door operator

  • US 4,952,080 A
  • Filed: 05/12/1989
  • Issued: 08/28/1990
  • Est. Priority Date: 05/12/1989
  • Status: Expired due to Term
First Claim
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1. A manually activatable assist control for an automatic door operator comprising:

  • drive means comprising at least one rotatable shaft employable for moving a door;

    encoder means rotatably coupled to a said shaft for generating a train of pulses in response to rotary motion of said shaft;

    direction selector means for selecting a pulse train of a predetermined rotatable direction;

    pulse shaper means for translating said directional pulse train to shape a wave form having pulses of pre-established width;

    integrator means for generating a DC signal having a DC wave form which is a function of the widths of said shaped wave form pulses;

    reference means for establishing a reference signal in response to the number of encoder pulses generated for a pre-established time interval;

    comparator means for comparing said DC signal to said reference signal and generating a power assist signal in the event said DC signal voltage exceeds said reference signal voltage;

    timer means responsive to said power assist signal for generating a hold open output signal for a pre-established time duration;

    output signal means responsive to said hold open output signal for transmitting an opening signal; and

    door control means for automatically controlling the drive means for opening and closing the door, said control means comprising an opening input means for triggering the door to an opening mode, said opening input means being responsive to said opening signal.

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