Piezoelectric actuator

A piezoelectric actuator comprising:

• a first piezoelectric layer having a plurality of first through holes;
• a first electrode layer disposed on one surface of the first piezoelectric layer, the first electrode layer connected to a power supply;
• a second piezoelectric layer disposed opposite to the first electrode layer with respect to the first piezoelectric layer in a first direction orthogonal to the surface of the first piezoelectric layer;
• and
• a second electrode layer disposed between the first piezoelectric layer and the second piezoelectric layer in the first direction,
• wherein the first electrode layer and the second electrode layer are electrically connected to each other via the plurality of first through holes of the first piezoelectric layer,
• wherein the second electrode layer includes a trunk portion and a plurality of branch portions branched from the trunk portion,
• wherein the trunk portion includes:
• a plurality of junction points from each of which a corresponding branch portion of the plurality of branch portions are branched;
• an end spaced from the plurality of junction points;
• and
• a second through hole positioned between the plurality of junction points and the end of the trunk portion,
• wherein the plurality of first through holes are grouped into a first group and a second group, and
• wherein the first group overlaps, in the first direction, a particular area defined between the end of the trunk portion and the second through hole and the second group overlaps, in the first direction, another particular area defined between the second through hole and the plurality of junction points.