| 摘要 |
PROBLEM TO BE SOLVED: To provide a structure protecting device which is activated, when an intruder is merely located by a conductive structure, and which is operated by the presence of the invader himself. SOLUTION: The device includes a transmission circuit 11 for transmitting a pulse signal and allowing it to flow in the ground; a detection circuit 13 for measuring the capacitance between the ground and the conductive structure 15 which is substantially insulated from the ground; a detection circuit 17 for detecting changes in the capacitance from the capacitance measured by the detection circuit 13; a comparison circuit 18 for comparing the change in the capacitance detected by the detecting circuit 17 with a reference value; an alarm device 19 for issuing an alarm, based on the comparison result in the comparison circuit 18. COPYRIGHT: (C)2005,JPO&NCIPI
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