Patent ID: 7638924

Claim:
A method of driving an ultrasonic transducer comprising the steps of: providing a piezoelectric resonator including a pair of electrodes sandwiching a piezoelectric body, and a backing layer disposed in contact with one of the pair of electrodes of the piezoelectric resonator and having the same acoustic characteristic impedance as the piezoelectric body; and driving the ultrasonic transducer so as to satisfy a condition: 2 Th≦Td≦ 6 Th where Th is a propagation time of an ultrasonic wave in the piezoelectric body sandwiched by the pair of electrodes, and Td is a pulse width of a drive pulse driving the piezoelectric resonator; wherein when a partition wall made of a substance different from a substance of an ultrasonic wave emission surface of the piezoelectric resonator and a substance to be a target of ultrasonic transmission is provided, the method further comprises the step of: setting a thickness of the partition wall so as to satisfy a condition: Td< 2 Lw/Vw where Lw is a thickness of the partition wall, and Vw is a sound speed when an ultrasonic wave propagates in the partition wall.