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Electromagnetic lock having distance-sensing monitoring system

  • US 8,820,803 B2
  • Filed: 03/02/2009
  • Issued: 09/02/2014
  • Est. Priority Date: 03/02/2009
  • Status: Expired
First Claim
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1. A door lock system configured to cooperate with a door movable in a door frame, the system being configured for sensing when said door in a locked mode is moved from a closed position toward an open position, and for allowing said door to become unlocked from said locked mode when said door is moved to an activation position after a subsequent delay, the system comprising:

  • a) an energizable electromagnet configured to be affixed to one of said door or said door frame for electromagnetically attracting an armature, said armature affixed to the other of said door or said door frame, wherein when said electromagnet is energized, said armature is attracted to said electromagnet when said door is in said locked mode;

    b) a permanent magnet configured to be mounted to one of said door or said door frame;

    c) a Hall Effect sensor configured for interacting with said permanent magnet and mounted to the other of said door or said door frame, wherein a distance between said Hall Effect sensor and said permanent magnet when said door is in said closed position defines a starting gap, and wherein said Hall Effect sensor is configured for detecting a plurality of instantaneous sensor separation distances between said Hall Effect sensor and said permanent magnet, said plurality of instantaneous sensor separation distances being any distance between and including when said door is in said closed position and when said door has reached said activation position;

    d) a starting gap adjustment mechanism having a selectable overall thickness, wherein said overall thickness of said starting gap adjustment mechanism is selected to adjustably set said starting gap; and

    e) a controller configured for receiving a varying signal from said Hall Effect sensor, said varying signal having varying voltage values that are correlated to said plurality of instantaneous sensor separation distances, wherein each of said plurality of instantaneous sensor separation distances are proportional to a corresponding instantaneous door separation distance between said door and said door frame as said door is moved from said closed position toward said activation position, wherein said varying voltage values define a slope of a graph of said voltage values as said door is moved from said closed position toward said activation position, wherein said slope of said graph of said varying voltage values is reduced as said overall thickness of said starting gap adjustment mechanism is increased, and wherein said overall thickness of said starting gap adjustment mechanism is selected to maximize said slope defined by said varying voltage values.

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