| 摘要 |
<p>PURPOSE:To inform the adhesion of a foreign material to an ultrasonic wave vibrator by detecting the operating status of the ultrasonic wave vibrator. CONSTITUTION:An ultrasonic wave vibrator 1 sends an ultrasonic wave pulse signal intermittently and receives a reflecting wave from a hindrance object when no transmission wave is in existence to detect the presence of the hindrance object within a detection range. The sensor is provided with a frequency detection means 11 detecting a resonance frequency of the ultrasonic wave vibrator 1 and a detection means 13 receiving a signal from the frequency detection means 11 and detecting a fault of the resonance frequency of the ultrasonic wave vibrator 1. The operating state of the ultrasonic wave vibrator 1 is detected by detecting the resonance frequency of the ultrasonic wave vibrator 1 to monitor the resonance frequency.</p> |
