Transducer and driving method thereof, and system

A transducer comprising:

• a piezoelectric element;
• and
• a film body including a film support portion having a hollow portion, and a vibration film connected to the film support portion and displaceable in a film thickness direction, the film body having the piezoelectric element stacked over the vibration film, wherein
• the piezoelectric element includes:
• a first electrode;
• a first stacked body having a first piezoelectric film and a second electrode;
• and
• a second stacked body having a second piezoelectric film and a third electrode, and separated from the first stacked body;
• the first piezoelectric film is sandwiched between the first electrode and the second electrode;
• the second piezoelectric film is sandwiched between the first electrode and the third electrode;
• the piezoelectric element and the film body form a vibration body;
• and
• the first stacked body and the second stacked body each have a driving voltage applied thereto, and are configured to be driven individually by the driving voltages respectively applied thereto to thereby change a resonant frequency of the vibration body.

A transducer comprising:

• a piezoelectric element;
• and
• a film body including a film support portion having a hollow portion, and a vibration film connected to the film support portion and displaceable in a film thickness direction, the film body having the piezoelectric element stacked over the vibration film, wherein
• the piezoelectric element includes:
• a first electrode;
• a second electrode;
• a piezoelectric film sandwiched between the first electrode and the second electrode;
• and
• a third electrode;
• the piezoelectric film is sandwiched between the first electrode and the third electrode;
• the third electrode is separated from the second electrode;
• each of the second electrode and the third electrode has a driving voltage applied thereto;
• the piezoelectric element and the film body form a vibration body;
• and
• the piezoelectric element is configured to change a resonant frequency of the vibration body by controlling the driving voltages applied to the second electrode and the third electrode individually.