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Glass-break shock sensor with validation

  • US 8,144,010 B2
  • Filed: 11/14/2007
  • Issued: 03/27/2012
  • Est. Priority Date: 11/14/2007
  • Status: Active Grant
First Claim
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1. An intrusion detector for a security system that detects the breaking of a glass in a window or a door and motion within a protected area comprising:

  • a single sensing section for detecting mechanical impact in a form of an acoustic signal on the window or glass and for detecting motion in a form of a motion induced signal within a protected area;

    a lens for focusing the motion induced signal;

    a first filter for filtering out a portion of the motion-induced signal which is not in a preset frequency band;

    a second filter for attenuating a portion of the acoustic signal outside a second preset frequency band;

    a microprocessor for determining if the detected acoustic signal is consistent with that required to break glass and if the detected motion induced signal is indicative of motion with the protected area; and

    an alarm generating section for generating an alarm based upon the determination of the microprocessor,wherein the single sensing section is capable of detecting a first change in electrical properties,wherein the microprocessor is capable of determining a cause of the first change in the electrical properties, activating a motion processing section only when the cause of the first change is a physical impact that is consistent with that required to break glass, and setting a preset detection time for said motion detection,wherein the microprocessor is capable of determining if a second change in electrical properties is detected within the preset detection time,wherein the microprocessor is capable of determining if the second change in electrical properties is indicative of motion if the second change is within the preset detection time, and determining if the second change in electrical properties is indicative of a physical impact that is consistent with that required to break glass if the second change is within the preset detection time,wherein, when it is determined that the first change is caused by a physical impact that is consistent with that required to break glass and the second change is caused by motion within the protected area within the preset detection time, the alarm generating section is capable of generating the alarm,wherein, when it is determined that the first change is caused by a physical impact that is consistent with that required to break glass and the second change is caused by a physical impact that is consistent with that required to break glass, the microprocessor is capable of resetting a timer to the preset detection time,wherein the microprocessor is capable of deactivating the motion processing section after expiration of the preset detection time, and ignoring said second change in electrical properties after the expiration of the preset detection time, andwherein said second change in electrical properties is received from the single sensing section within and outside of the preset detection time, but said second change in electrical properties is not processed for motion if the second change in electrical properties is not within the preset detection time.

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