Abstract: A first active region is made of a piezoelectric overlaps a midsection of a pressure chamber when viewed in plan through a pressure applying surface. A second active region is made of a piezoelectric member closer than the first active region to the pressure applying surface. The second active region extends over both a peripheral section of the pressure chamber and an outer region located outside the pressure chamber when viewed in plan through the pressure applying surface. A driver controls intensity of a first electric field applied to the first active region and intensity of a second electric field applied to the second active region such that the time period over which the first active region contracts and the time period over which the second active region contracts overlap or coincide with each other. The first electric field is more intense than the second electric field.

Abstract: In a piezoelectric ceramic composition including potassium sodium niobate, a transition temperature at which a phase transition between an orthorhombic crystal structure and a tetragonal crystal structure occurs lies in a temperature range of ?20° C. or higher and 60° C. or lower. In the piezoelectric ceramic composition, ?t/?o is 0.72 or more, where ?o represents a coefficient of linear expansion determined when a crystal structure is orthorhombic in the temperature range, and ?t represents a coefficient of linear expansion determined when a crystal structure is tetragonal in the temperature range.

Abstract: A first active region is made of a piezoelectric overlaps a midsection of a pressure chamber when viewed in plan through a pressure applying surface. A second active region is made of a piezoelectric member closer than the first active region to the pressure applying surface. The second active region extends over both a peripheral section of the pressure chamber and an outer region located outside the pressure chamber when viewed in plan through the pressure applying surface. A driver controls intensity of a first electric field applied to the first active region and intensity of a second electric field applied to the second active region such that the time period over which the first active region contracts and the time period over which the second active region contracts overlap or coincide with each other. The first electric field is more intense than the second electric field.

Abstract: A piezoelectric ceramic composition is represented by a composition formula AxBO3 and includes potassium sodium niobate containing K and Na that account for 80% or more of an amount of A-site elements and containing Nb that accounts for 70% or more of an amount of B-site elements. The piezoelectric ceramic composition contains Ta and Fe at a B-site.

Abstract: A piezoelectric actuator includes a common electrode on a piezoelectric layer at a first side adjacent to a first surface and extends over a plurality of piezoelectric elements. A plurality of first individual electrodes is on the piezoelectric layer at a second side adjacent to a second surface. Each of the plurality of first individual electrodes is at a piezoelectric element of the plurality of piezoelectric elements, and are not electrically connected together. A first insulating layer is on the common electrode at the first side and extends over the plurality of piezoelectric elements. A plurality of second individual electrodes is on the first insulating layer at the first side. Each of the plurality of second individual electrodes is at a piezoelectric element of the plurality of piezoelectric elements, and overlap centers of the plurality of first individual electrodes. The plurality of second individual electrodes are electrically connected together.

Abstract: Provided is a piezoelectric ceramic composition including a potassium sodium niobate-based perovskite type complex oxide represented by Compositional Formula ABO3, as a main component. Further, the piezoelectric ceramic composition contains Bi in an A site and Zr in a B site. Further, the piezoelectric ceramic composition includes a segregation portion positioned in a crystal grain. At least one of Zr or Bi is localized in the segregation portion.

Abstract: A first active region is made of a piezoelectric overlaps a midsection of a pressure chamber when viewed in plan through a pressure applying surface. A second active region is made of a piezoelectric member closer than the first active region to the pressure applying surface. The second active region extends over both a peripheral section of the pressure chamber and an outer region located outside the pressure chamber when viewed in plan through the pressure applying surface. A driver controls intensity of a first electric field applied to the first active region and intensity of a second electric field applied to the second active region such that the time period over which the first active region contracts and the time period over which the second active region contracts overlap or coincide with each other. The first electric field is more intense than the second electric field.

Abstract: A piezoelectric actuator includes a piezoelectric layer and a conductor layer that is provided directly or indirectly on the piezoelectric layer. In plan view, the conductor layer includes a plurality of individual electrodes that are arranged with intervals therebetween and a plurality of wiring lines that extend from the plurality of individual electrodes. Each wiring line includes a wide portion and a first narrow portion. The wide portion includes a part positioned at a center of the wiring line in a length direction. The first narrow portion is disposed between the wide portion and one of the plurality of individual electrodes to which the wiring line is connected. The first narrow portion has a width less than a width of the wide portion.

Abstract: A piezoelectric actuator includes a common electrode on a piezoelectric layer at a first side adjacent to a first surface and extends over a plurality of piezoelectric elements. A plurality of first individual electrodes is on the piezoelectric layer at a second side adjacent to a second surface. Each of the plurality of first individual electrodes is at a piezoelectric element of the plurality of piezoelectric elements, and are not electrically connected together. A first insulating layer is on the common electrode at the first side and extends over the plurality of piezoelectric elements. A plurality of second individual electrodes is on the first insulating layer at the first side. Each of the plurality of second individual electrodes is at a piezoelectric element of the plurality of piezoelectric elements, and overlap centers of the plurality of first individual electrodes. The plurality of second individual electrodes are electrically connected together.

Abstract: A piezoelectric ceramic composition is represented by a composition formula AxBO3 and includes potassium sodium niobate containing K and Na that account for 80% or more of an amount of A-site elements and containing Nb that accounts for 70% or more of an amount of B-site elements. The piezoelectric ceramic composition contains Ta and Fe at a B-site.

Abstract: In a piezoelectric ceramic composition including potassium sodium niobate, a transition temperature at which a phase transition between an orthorhombic crystal structure and a tetragonal crystal structure occurs lies in a temperature range of ?20° C. or higher and 60° C. or lower. In the piezoelectric ceramic composition, ?t/?O is 0.72 or more, where ?O represents a coefficient of linear expansion determined when a crystal structure is orthorhombic in the temperature range, and ?t represents a coefficient of linear expansion determined when a crystal structure is tetragonal in the temperature range.