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Passive infrared motion detector and method

  • US 6,215,399 B1
  • Filed: 11/10/1997
  • Issued: 04/10/2001
  • Est. Priority Date: 11/10/1997
  • Status: Expired due to Term
First Claim
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1. A method of detecting an intruder using a dual PIR sensor motion detector comprising the steps of:

  • collecting infrared radiation from first and second arrays of detection zones, said zones each having a predetermined elevation direction with respect to a vertical direction for reaching a predetermined range and having a predetermined azimuth plane with respect to a horizontal direction, wherein;

    each one of said zones in said first array corresponds substantially to a respective one of said zones in said second array;

    said corresponding zones have substantially the same shape, solid angle and azimuth direction;

    ones of said corresponding zones reaching a close range have different said elevation directions to provide zone separation, whereby short infrared emitting objects only cross one of said corresponding zones of said first and second arrays;

    ones of said corresponding zones reaching a far range have substantially the same said elevation direction to provide almost no zone separation, whereby small animals crossing said first and second array of zones at a close range do not result in said alarm signal being generated;

    detecting said collected radiation using first and second PIR sensors, associated respectively with said first and second arrays, said first PIR sensor outputting a first sensor signal and said second PIR sensor outputting a second sensor signal; and

    generating an alarm signal when both said first and second sensor signals simultaneously indicate intruder motion across said corresponding zones, whereby false alarms are reduced.

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