An ultrasonic range finder which can effectively suppress the influence of direct transmission waves is provided. An ultrasonic range finder according to the present invention comprises a transmitting ultrasonic sensor, a receiving ultrasonic sensor, and a case which holds both ultrasonic sensors mounted...http://www.google.fr/patents/US5907521?utm_source=gb-gplus-shareBrevet US5907521 - Ultrasonic range finder using ultrasonic sensor
