| 摘要 |
PURPOSE:To make it possible to detect with high accuracy by using an ultrasonic transmitter and its receiver which have been provided so as to be opposed on the surface of an object to be detected, utilizing an ultrasonic dead phenomenon, and detecting the surface position. CONSTITUTION:An ultrasonic transmission element 1 and its receiving element 2 are opposed on the surface of an object to be detected 3, and are arranged at a constant interval L1. When a distance D1 between the surface of the receiving element 2 and the surface of the object to be detected 3 is varied, the output of the receiving element 2 is varied pulsatively, and when said D1 is between a distance d1 and d2 (about 10mm.), an ultrasonic dead phenomenon is caused, and the output is lowered abruptly. Also, even when it is between a distance d3 and d4 (about 28mm.), the dead phenomenon is caused, as well. When said phenomenon is utilized, it is also possible to detect with high accuracy a water-level of an automatic equipment which maintains a water-level varied in the vessel at the position between d1 and d3. In this way, it is possible to detect the surface with high accuracy by a simple constitution. |
