Patent ID: 7460439

Claim:
A multiple resonances type ultrasonic transducer for a ranging measurement using a parametric transmitting array in air, comprising: an ultrasonic actuator unit formed with a regularly mixing array of first unit actuators having a resonance frequency of f 1 and second unit actuators having a resonance frequency of f 2 , for generating a difference frequency wave (f d =f 1 −f 2 ) with high directionality by forming a parametric transmitting array in air through generating two ultrasonic waves with high pressure in air; and an ultrasonic sensor unit formed with one or more unit sensors having a resonance frequency of the difference frequency (f d =f 1 −f 2 ) , for sensing a reflected ultrasonic wave signal from a target, wherein the difference frequency (f d ) is selected within a range of about 20kHz ˜60kHz.