| 摘要 |
<p>A piezoelectric ultrasonic transducer is triggered by a predeflection of the transducer in a first direction with a square-wave pulse or a saw-tooth pulse which has a rapidly dropping trailing edge to effect deflection in the opposite direction, with an overshoot. At the maximum point of overshoot, an alternating triggering voltage, preferably in the form of a pulse sequence, is applied to energize and maintain the transducer in resonance oscillation.</p> |
