| 摘要 |
Ultrasonic wave has conventionally been used in depth measuring or fish detecting in water, and a ceramic vibrator based on a piezo-effect principle is very often used as a device for emitting this ultrasonic wave. A ultrasonic wave emitting-wave transmitter/receiver by a ceramic vibrator based on this piezo principle and having a better emission efficiency than before. Almost all the ceramic vibrator-based ultrasonic vibrators currently available use one frequency as a frequency that can be efficiently emitted from one vibrator, because a ceramic vibrator has only one portion where the most efficient natural oscillation frequency is available. Improvement has been made so that a second natural oscillation frequency offered by a combination of a ceramic vibrator and a steel block is available, in addition to the best natural oscillation frequency provided by a ceramic vibrator, to coexist with the ceramic vibrator's natural oscillation frequency, whereby the improvement is such that two ultrasonic wave frequencies can be used with only one vibrator.
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