| 摘要 |
<p>An aerial ultrasonic sensor which can be used outdoors and has a high degree of design flexibility. The sensor comprises an outer case (10) which is cylindrical and whose end is not closed but opened to form a sound discharge port (10a), and a vibrator (23) including a piezoelectric ceramics (14) disposed within the outer case (10), with a drainage through-hole (10c) formed in the lateral surface of the outer case (10). When the sensor is used outdoors with the through-hole (10c) directed downward, rain water entering the outer case (10) flows out through the through-hole (10c), so that it never collects in the outer case (10) to affect the vibrator (23).</p> |
