Liquid ejection head and recording apparatus

A liquid ejection head comprising

• a channel member comprising a pressure applying surface, and a pressure chamber comprising an opening defined in the pressure applying surface;
• a piezoelectric actuator disposed on the pressure applying surface, wherein a thickness direction is perpendicular to the pressure applying surface, the piezoelectric actuator comprising:
• a first active region made of a piezoelectric member polarized in the thickness direction, the first active region extending over a midsection of the pressure chamber when viewed in a plan view through the pressure applying surface, and
• a second active region made of another piezoelectric member polarized in the thickness direction and closer than the first active region to the pressure applying surface, the second active region extending over both a peripheral section of the pressure chamber and an outer region located outside the pressure chamber when viewed in the plan view through the pressure applying surface;
• and
• a driver configured to drive the piezoelectric actuator and to perform liquid ejection control for ejecting liquid, the liquid ejection control including control of an intensity of a first electric field applied to the first active region in the thickness direction and an intensity of a second electric field applied to the second active region in the thickness direction in at least one of a first manner in which a time period over which the first active region expands along the pressure applying surface and a time period over which the second active region expands along the pressure applying surface overlap or coincide with each other or a second manner in which a time period over which the first active region contracts along the pressure applying surface and a time period over which the second active region contracts along the pressure applying surface overlap or coincide with each other;
• wherein
• one surface of the piezoelectric actuator located on a first side is farther from the channel member than another surface of the piezoelectric actuator located on a second side,
• the piezoelectric actuator comprises
• a first piezoelectric layer, a second piezoelectric layer, a third piezoelectric layer, and a fourth piezoelectric layer stacked in sequence from the first side to the second side,
• a first electrode disposed on a surface of the first piezoelectric layer on the first side, the first electrode extending over the midsection in a see-through plan view,
• a second electrode disposed on a surface of the first piezoelectric layer on the second side, the second electrode extending over the midsection in the see-through plan view,
• a third electrode disposed on a surface of the second piezoelectric layer on the second side, the third electrode extending over the midsection, the peripheral section, and the outer region in the see-through plan view, and
• a fourth electrode disposed on a surface of the fourth piezoelectric layer on the second side, the fourth electrode extending over the peripheral section and the outer region in the see-through plan view,
• the first active region comprises
• a region of the first piezoelectric layer that is located between the first electrode and the second electrode,
• a region of the second piezoelectric layer that is located between the second electrode and a portion included in the third electrode that extends over the midsection, and
• the second active region comprises
• a region of the third and fourth piezoelectric layers this is located between the fourth electrode and a portion included in the third electrode that extends over the peripheral section and the outer region.

A liquid ejection head comprising

• a channel member comprising a pressure applying surface, and a pressure chamber comprising an opening defined in the pressure applying surface;
• a piezoelectric actuator disposed on the pressure applying surface, wherein a thickness direction is perpendicular to the pressure applying surface, the piezoelectric actuator comprising:
• a first active region made of a piezoelectric member polarized in the thickness direction, the first active region extending over a midsection of the pressure chamber when viewed in a plan view through the pressure applying surface, and
• a second active region made of another piezoelectric member polarized in the thickness direction and closer than the first active region to the pressure applying surface, the second active region extending over both a peripheral section of the pressure chamber and an outer region located outside the pressure chamber when viewed in the plan view through the pressure applying surface;
• and
• a driver configured to drive the piezoelectric actuator and to perform liquid ejection control for ejecting liquid, the liquid ejection control including control of an intensity of a first electric field applied to the first active region in the thickness direction and an intensity of a second electric field applied to the second active region in the thickness direction in at least one of a first manner in which a time period over which the first active region expands along the pressure applying surface and a time period over which the second active region expands along the pressure applying surface overlap or coincide with each other or a second manner in which a time period over which the first active region contracts along the pressure applying surface and a time period over which the second active region contracts along the pressure applying surface overlap or coincide with each other;
• wherein in a sectional view taken along a line passing through a center of the pressure chamber and orthogonal to the pressure applying surface, a width of a second portion of the second active region that is located outside the pressure chamber is greater than a width of a first portion of the second active region that extends over the pressure chamber.

A liquid ejection head, comprising:

• a channel member comprising a pressure applying surface and a pressure chamber comprising an opening defined in the pressure applying surface;
• a piezoelectric actuator disposed on the pressure applying surface, wherein
• a thickness direction is perpendicular to the pressure applying surface, the piezoelectric actuator comprising:
• a first active region made of a piezoelectric member polarized in the thickness direction, the first active region extending over a midsection of the pressure chamber when viewed in a plan view through the pressure applying surface, and
• a second active region made of another piezoelectric member polarized in the thickness direction and closer than the first active region to the pressure applying surface, the second active region extending over both a peripheral section of the pressure chamber and an outer region located outside the pressure chamber when viewed in the plan view through the pressure applying surface;
• and
• when performing control for ejecting liquid droplets, the driver controls intensity of an electric field applied to the first active region in the thickness direction and intensity of an electric field applied to the second active region in the thickness direction in such a manner that a time period over which the first active region expands along the pressure applying surface and a time period over which the second active region expands along the pressure applying surface overlap or coincide with each other and a time period over which the first active region contracts along the pressure applying surface and a time period over which the second active region contracts along the pressure applying surface overlap or coincide with each other, and
• an area of a second portion of the second active region that is located outside the pressure chamber is greater than an area of a first portion of the second active region that extends over the pressure chamber when the second active region is viewed in the plan view through the pressure applying surface.

A liquid ejection head, comprising:

• a channel member comprising a pressure applying surface, and a pressure chamber comprising an opening defined in the pressure applying surface;
• a piezoelectric actuator disposed on the pressure applying surface;
• and
• a driver configured to drive the piezoelectric actuator, wherein
• a thickness direction is perpendicular to the pressure applying surface, the piezoelectric actuator comprising:
• a first active region made of a piezoelectric member polarized in the thickness direction, the first active region extending over a midsection of the pressure chamber when viewed in a plan view through the pressure applying surface,
• a second active region made of another piezoelectric member polarized in the thickness direction and closer than the first active region to the pressure applying surface, the second active region extending over both a peripheral section of the pressure chamber and an outer region located outside the pressure chamber when viewed in the plan view through the pressure applying surface, and
• an inactive region made of a piezoelectric member and extending to a perimeter of the first active region,
• the driver performs liquid ejection control by which intensity of an electric field applied to the first active region in the thickness direction and intensity of an electric field applied to the second active region in the thickness direction are controlled in at least one of a first manner in which a time period over which the first active region expands along the pressure applying surface and a time period over which the second active region expands along the pressure applying surface overlap or coincide with each other or a second manner in which a time period over which the first active region contracts along the pressure applying surface and a time period over which the second active region contracts along the pressure applying surface overlap or coincide with each other, and
• when not performing the liquid ejection control, the driver performs reorientation control by which an electric field is applied to the inactive region in the thickness direction.

A liquid ejection head comprising

• a channel member comprising a pressure applying surface, and a pressure chamber comprising an opening defined in the pressure applying surface;
• a piezoelectric actuator disposed on the pressure applying surface, wherein a thickness direction is perpendicular to the pressure applying surface, the piezoelectric actuator comprising:
• a first active region made of a piezoelectric member polarized in the thickness direction, the first active region extending over a midsection of the pressure chamber when viewed in a plan view through the pressure applying surface, and
• a second active region made of another piezoelectric member polarized in the thickness direction and closer than the first active region to the pressure applying surface, the second active region extending over both a peripheral section of the pressure chamber and an outer region located outside the pressure chamber when viewed in the plan view through the pressure applying surface;
• and
• a driver configured to drive the piezoelectric actuator and to perform liquid ejection control for ejecting liquid, the liquid ejection control including control of an intensity of a first electric field applied to the first active region in the thickness direction and an intensity of a second electric field applied to the second active region in the thickness direction in at least one of a first manner in which a time period over which the first active region expands along the pressure applying surface and a time period over which the second active region expands along the pressure applying surface overlap or coincide with each other or a second manner in which a time period over which the first active region contracts along the pressure applying surface and a time period over which the second active region contracts along the pressure applying surface overlap or coincide with each other;
• wherein a piezoelectric member located on a side opposite to the pressure applying surface with respect to the second active region and extending to a perimeter of the first active region is an inactive region over a thickness of the first active region.