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Energy saving motor-driven locking subsystem

  • US 7,006,799 B2
  • Filed: 09/30/2002
  • Issued: 02/28/2006
  • Est. Priority Date: 09/30/2001
  • Status: Expired due to Term
First Claim
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1. In an RF access control system, a method for reducing the power used to lock or unlock an access point, said access point including a locking shaft, a motor driving said locking shaft and a motor armature, and an electronic control processor controlling said motor;

  • said method including the steps of;

    providing power to a motor during an initial drive time so that a locking shaft is set in motion;

    ceasing to supply power to said motor;

    periodically measuring the back EMF from said motor during a time interval when the motor armature has a substantially zero current value and summing the measurements of said back EMF to form a summed back EMF measurement;

    comparing said summed back EMF measurement to a predetermined threshold;

    again providing power to said motor if said summed back EMF measurement is less than said predetermined threshold.

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