| 摘要 |
<p>PROBLEM TO BE SOLVED: To eliminate restrictions on installation locations like a PIR sensor and prevent the generation of malfunctions such as a switch sensor by turning on a switch to operate room equipment for the fixed time at the time of a sound wave detector detecting sound wave of low frequency. SOLUTION: A microphone collects sound in a room. A low-frequency LF signal of 1 Hz or less out of collected sound wave passes an LPF 12 and is amplified by an amplifier 14, and an LF detection signal d1 is outputted at the time of exceeding a first threshold in a first comparator 16. An ultrasonic HF signal of 20 kHz or more out of the sound wave collected by the microphone passes an HPF 15 and is amplified by an amplifier 15, and an HF detection signal d2 is outputted at the time of exceeding a second threshold in a comparator 17. Since action is started upon detection of a sound wave, there is no rectrictions on installation location and low frequency generated is about 1 Hz, it can be distinguished from the sounds of other physical phenomena so that there is no malfunction.</p> |
