Ultrasonic transducer

An ultrasonic transducer comprising:

• a case having a plurality of ultrasonic wave emission holes;
• and
• an ultrasonic wave generator that includes a first piezoelectric vibrator and a second piezoelectric vibrator,
• wherein the ultrasonic wave generator is disposed in the case to define a plurality of first acoustic paths that extend from the first piezoelectric vibrator to the plurality of ultrasonic wave emission holes, respectively, and a plurality of second acoustic paths that extend from the second piezoelectric vibrator to the plurality of ultrasonic wave emission holes, respectively,
• wherein each of the piezoelectric vibrators are configured to generate an ultrasonic wave that creates air resonance in the first and second acoustic paths, respectively,
• wherein all of the first acoustic paths extend from a center region of a surface of the first piezoelectric vibrator at which displacement is greatest during excitation to the plurality of ultrasonic wave emission holes and are equal in distance to each other, and
• wherein all of the second acoustic paths extend from a center region of a surface of the second piezoelectric vibrator at which displacement is greatest during excitation to the plurality of ultrasonic wave emission holes and are equal in distance to each other.