ULTRASONIC WAVE TRANSMITTER-RECEIVER

摘要

PROBLEM TO BE SOLVED: To correctly measure a distance up to an obstacle by preventing rain drops from being deposited onto an inner wall of a horn of an ultrasonic wave transmitter-receiver so as to prevent an ultrasonic wave sent from an ultrasonic wave vibrator from being irregularly reflected in the horn due to the rain drops sticking on the inner wall of the horn. SOLUTION: A hydrophilicity is provided to the inner wall of a horn 13. For example, surface treatment with a hydrophilic agent is applied to the inner wall so as to avoid rain drops from being caused even when rainwater is deposited onto the inner wall of the horn 13, then an ultrasonic wave emitted from an ultrasonic wave vibrator 12 is not irregularly reflected in the inside of the horn 13, and thus a distance up to an obstacle can correctly be measured.