| 摘要 |
<p>An ultrasonic distance measuring device comprising a pulse generator (1) generating a first pulse (6), a transducer circuit (9, 10, 11, 12, 13) converting the first pulse (6) into, and transmitting, an ultrasonic signal with a duration shorter than the first pulse (6), another transducer circuit (19, 20, 21) detecting the ultrasonic signal and converting it into a second pulse (22, 32) with a duration shorter than the first pulse (6), a logic circuit (16) receiving the first (6) and second (22, 32) pulses and generating a third pulse (23) when the second pulse (22, 32) only is input, and a time counter (17) receiving the first (16) and third (23) pulses and measuring a time interval therebetween. The transmitted ultrasonic signal has a duration sufficiently short for accurate short distance measurement. Interterence between ultrasonic signals received directly and those reflected from targets is eliminated.</p> |
