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System and method for detecting and monitoring shell cracks on freight containers

  • US 7,688,217 B2
  • Filed: 08/15/2006
  • Issued: 03/30/2010
  • Est. Priority Date: 08/17/2005
  • Status: Expired due to Fees
First Claim
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1. A device for detecting shell cracks of a freight container, the device comprising:

  • a plurality of sensing units, the plurality of sensing units being distributed in an internal surface of the container, each sensing unit corresponding to an identification code;

    wherein the sensing unit comprises;

    a plurality of mesh electrical circuits embedded in an insulated baseboard;

    a first resistor and a second resistor set in the mesh electrical circuits;

    a first end of the second resistor is connected with the first resistor and a second end of the second resistor is grounded;

    the number of the sensing units in the device is N, the first resistors in each of the sensing units are linked together in series via the mesh electrical circuits to form series and parallel circuits containing N first resistors and N second resistors;

    a selection of a resistance of the resistors in the sensing unit is based on maximizing a variation of resistance between ends of the series and parallel circuits formed by N first resistors and N second resistors and the ground when a break occurs in the mesh electrical circuits;

    an interface circuit;

    a receiver module;

    a computer processing unit (CPU); and

    an alarm unit;

    whereby a signal generated from one of the sensing units is transmitted to the CPU via the interface circuit and receiver module and an output signal from the CPU is transmitted to the alarm unit.

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