| 摘要 |
<p>An ultrasonic searcher of the sonar type with wave-transmitting and -receiving electroacoustic conversion means has complicated electric circuits and has the disadvantage that erroneous operations due to turbulent flow can occur. This sensor forms a prescribed sound field in the space with a single wave-transmitting and -receiving electroacoustic conversion means, and detects the intrusion of a moving body by variations in the sound field, thereby solving the above drawbacks. The sensor has a high-frequency power source (2), electroacoustic conversion means (1), and an element (3) of a prescribed impedance, the means (1) and (3) form an ultrasonic moving-body sensor connected in series with the power source (2). The sensor has detection means for detecting variations in either the voltage between the terminals of the electroacoustic conversion means (1) or the voltage between the terminals of the constant impedance element (3).</p> |
