| 摘要 |
PROBLEM TO BE SOLVED: To provide an ultrasonic level gage in which a driving frequency is adjusted by a simple control circuit and in which the amplitude of a received signal is made maximum. SOLUTION: In an ultrasonic level gage, a drive circuit 10 which outputs a driving signal at a variable driving frequency fd is provided, a piezoelectric element 20 which radiates ultrasonic waves according to the driving signal of the drive circuit 10 is provided, and a receiving circuit 30 which receives reflected waves received by the piezoelectric element 20 is provided. A driving- frequency adjusting circuit 40 which adjusts the driving frequency fd is provided in such a way that the driving frequency fd agrees with the natural frequency of the piezoelectric element 20. |
