ULTRASONIC LIQUID LEVEL DETECTING DEVICE

PURPOSE:To detect a liquid level with high precision by calculating an attenuation constant from the height and path of a pulse reflection echo corresponding to the medium in a container and detecting the boundary surface between two media in the container. CONSTITUTION:Ultrasonic wave pulses which are made incident from the external wall of the container 1 by a probe 2 causes multi-path reflection inside and outside the wall of the container and time variation of an echo outputted through the probe 2 and a probe driving circuit 3 is outputted as TB1. Then, a wave memory 11 performs sampling to hold a digital value TB2. Further, digital data is held in a RAM15 through a data I/O 12 and a CPU14. The time when the height of a peak echo appears is detected from those data. Then, peak values A1, A2... and paths T1, T2... of respective reflection echoes are obtained as shown by TB3 and then the attenuation constant is calculated. The obtained attenuation constant is selected in the table of attenuation constants stored in a ROM16 to decide on the name of the corresponding medium, and the medium name, plate thickness, etc., are displayed on a display device.