Inkjet head

An inkjet head comprising:

• a nozzle hole through which droplets are ejected;
• a pressure chamber so provided as to communicate with the nozzle hole;
• and
• a piezoelectric device disposed on the side opposite to the nozzle hole, and causing a pressure change inside the pressure chamber, wherein
• a cross-sectional shape of the pressure chamber in a direction substantially perpendicular to an arrangement direction where the pressure chamber and the piezoelectric device are arranged includes a circular-arc-shaped side wall portion that has a substantially circular-arc shape on the supply side for liquid supply to the pressure chamber, and linear side wall portions connected with two ends of the circular-arc-shaped side wall portion on the side opposite to the supply side, and forming such a shape that the distance between the linear side wall portions gradually decreases toward the side opposite to the supply side,
• the piezoelectric device includes a displacement portion that causes the pressure change inside the pressure chamber by displacement of the piezoelectric device, and an electrode connection portion electrically connecting the piezoelectric device and an electrode,
• a cross-sectional shape of the displacement portion in the direction substantially perpendicular to the arrangement direction includes a circular-arc-shaped portion that is formed inside the circular-arc-shaped side wall portion into a shape substantially equivalent to the shape formed by the circular-arc-shaped side wall portion as viewed in the arrangement direction, and has a smaller cross section in the direction substantially perpendicular to the arrangement direction than a corresponding cross section of the shape formed by the circular-arc-shaped side portion,
• the cross-sectional shape of the displacement portion in the direction substantially perpendicular to the arrangement direction further includes a linear portion that is formed inside the linear side wall portions into a shape substantially equivalent to the shape formed by the linear side wall portions as viewed in the arrangement direction, and has a smaller cross section in the direction substantially perpendicular to the arrangement direction than a corresponding cross section of the shape formed by the linear side portions, and
• the electrode connection portion is connected to the linear portion on the side opposite to the circular-arc-shaped portion in such a position as to overlap with a side wall portion of the pressure chamber in the arrangement direction.