| 摘要 |
PROBLEM TO BE SOLVED: To provide a crime preventing device for surely detecting any breakdown act to a storage container for storing cash or noble metals such as a cash box or a device for dealing with cash such as a cash dispenser or an automatic vending machine with a few sensors. SOLUTION: A microphone 3 and a speaker 9 are arranged in a crime prevention target which is internally provided with a space, and a sound is generated from the speaker 9, and collected by the microphone 3 so that a sound pressure change due to the change of acoustic impedance in the crime prevention target can be detected. Thus, it is possible to easily detect a hole opening due to the burn-off act of the whole crime prevention target. COPYRIGHT: (C)2005,JPO&NCIPI
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