| 摘要 |
PROBLEM TO BE SOLVED: To provide a security magnetic sensor that does not accept a malicious work. SOLUTION: The security magnetic sensor 50 has a first magnetic sensor 70 that is operated by a first magnetic field and a second magnetic switch 60 that is operated by a second magnetic field stronger than the first magnetic field. The first magnetic switch 70 is electrically connected in series to the second magnetic switch 60. In a home position, the first magnetic switch 70 is in an open state, and the second magnetic switch 60 is in a closed state. When the security magnetic sensor 50 is normally operated, the first magnetic switch 70 is operated so as to be closed. However, when the security magnetic sensor 50 is applied a malicious work by addition of an auxiliary magnet 90, it gives an alarm sound with the second magnetic switch 60 in open state. COPYRIGHT: (C)2008,JPO&INPIT
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