Piezoelectric actuator inkjet head and method of forming the same

A piezoelectric actuator of an inkjet head, the piezoelectric actuator comprising:

• a vibration plate;
• a lower electrode formed on the vibration plate;
• a piezoelectric layer formed on the lower electrode;
• an upper electrode having a first portion disposed on the piezoelectric layer and a second portion extended from the first portion in a first direction, the first portion having a first width in a second direction perpendicular to the first direction, and the second portion having a second width wider than the first width in the second direction;
• and
• a supporting pad disposed between the lower electrode and the second portion of the upper electrode.

An inkjet head usable in an image forming apparatus, comprising:

• an ink flow structure having a flow channel plate and a nozzle plate disposed on a first side of the flow channel plate to form a pressure chamber;
• and
• a piezoelectric actuator having a vibration plate disposed on a second side of the flow channel plate, a lower electrode formed on the vibration plate, a piezoelectric layer formed on the lower electrode at a position corresponding to the pressure chamber, a supporting pad formed on the lower electrode and contacting one end of the piezoelectric layer to be extended away from the one end of the piezoelectric layer, and an upper electrode extending from a top surface of the piezoelectric layer to a top surface of the supporting pad,
• wherein the upper electrode is bonded to a driving circuit above the supporting pad to receive a voltage from the driving circuit.

An inkjet head usable in an image forming apparatus, comprising:

• an ink flow structure having a flow channel plate and a nozzle plate disposed on a first side of the flow channel plate to form a pressure chamber;
• and
• a piezoelectric actuator having a vibration plate disposed on a second side of the flow channel plate, a lower electrode formed on the vibration plate, a piezoelectric layer formed on the lower electrode, and an upper electrode having a first portion disposed on the piezoelectric layer and a second portion extended from the first portion in a first direction to be connected to a signal line, the first portion having a first width in a second direction perpendicular to the first direction, and the second portion having a second width wider than the first width in the second direction;
• and
• a supporting pad disposed between the lower electrode and the second portion of the upper electrode.