| 摘要 |
PURPOSE:To avoid interference between receiving means by differentiating the detecting characteristics thereof from each other depending on the maximum pass value in the pass band characteristics of receiving means. CONSTITUTION:The liquid level gauge 10 comprises a plurality of ultrasonic transmitting/receiving means A, B, C corresponding to a plurality of liquid levels 1-3 mounted on the outer wall face 12 of a liquid vessel 11 wherein the means A, B, C comprise ultrasonic transmitting means A1, B1, C1 and receiving means A2, B2, C2. The receiving means A2, B2 and C2 have ultrasonic detection characteristics corresponding, respectively, to the primary, secondary and tertiary characteristic values in the pass band characteristics of the transmitting means A1, B2 and C1. This structure can be achieved by simply varying the thickness of piezoelectric oscillators constituting the receiving means A2, B2 and C2. This structure prevents each receiving means from erroneous function and interference. |
