GLASS DESTRUCTION DETECTION DEVICE

Japanese Patent JP3792006

B2

PROBLEM TO BE SOLVED: To surely detect the destruction of glass and to prevent the malfunctions due to other noise sounds by detecting the sound wave generated by the destruction of glass and analyzing this sound waveform to judge the presence or absence of a square wave. SOLUTION: A condenser microphone 1 having the flat characteristic of band is used to detect the sound wave that is generated by the destruction of glass and then transmitted into a space. The output of the microphone 1 is amplified by an amplifier 2 and outputted to an LPF 3. An output analog signal is converted into a digital signal by an A/D converter 4 and recorded in a memory 5. A square wave detection means 6 consists of two LPF 61 and 62 and a CPU 63 and performs the signal processing via the numeric calculation when the signal recorded in the memory 5 exceeds a prescribed level to judge the presence or absence of the destruction of glass. When the destruction of glass is decided, this judged result is sent to an alarm output part 7. Then, an alarm is outputted to the outside.