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Methods and apparatus for security device portal sensing

  • US 7,663,483 B2
  • Filed: 12/13/2007
  • Issued: 02/16/2010
  • Est. Priority Date: 12/16/2006
  • Status: Expired due to Fees
First Claim
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1. A security device for detecting that detects movement of a provided portal cover, the security device comprising:

  • a sensor that provides indicia of a magnitude of a magnetic flux through the sensor;

    a magnet that provides the magnetic flux through the sensor; and

    a processor that receives the indicia of the magnitude of the magnetic flux and detects a change in the magnitude of the magnetic flux outside an upper boundary and a lower boundary of a first threshold and an upper boundary and a lower boundary of a second threshold;

    wherein;

    the sensor does not move with respect to the magnet;

    movement of the sensor and with respect to at least one of the portal cover and a portal changes the magnitude of the magnetic flux through the sensor;

    the processor determines an average value of a series of values of the indicia of the magnitude of the magnetic flux that fall within the upper boundary and the lower boundary of the first threshold; and

    the upper boundary and the lower boundary of the first threshold and the second threshold respectively are set in accordance with the average value.

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