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System and related methods for detecting an obstruction in the path of a garage door controlled by an open-loop operator

  • US 5,929,580 A
  • Filed: 08/05/1997
  • Issued: 07/27/1999
  • Est. Priority Date: 08/05/1997
  • Status: Expired due to Term
First Claim
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1. An internal entrapment system for a garage door controlled by an open loop garage door operator, comprising:

  • a counter-balancing system for transferring the garage door from a first to a second position, wherein said counter-balancing system includes a motor with a drive shaft that only drives the door from said first position to said second position, said counter-balancing system allowing the door to move from said second position to said first position and allowing rotation of said drive shaft;

    means for detecting a speed of the garage door during transfer between first and second positions solely from said drive shaft;

    means for determining a plurality of positional locations of the garage door during transfer between first and second positions, wherein said determining means is separate from said detecting means; and

    controller means for calculating a motor torque value from said detecting means for each of said plurality of positional locations from said determining means to compare with a plurality of door profile data points, wherein said controller means takes corrective action if the difference between the motor torque value for any one of said plurality of positional locations goes beyond a predetermined threshold for a respective one of said plurality of door profile data points, otherwise said controller means updates said plurality of door profile data points to the motor torque values for each respective said plurality of positional locations.

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