Patent ID: 7380916

Claim:
A liquid delivery apparatus comprising: a pressure chamber accommodating a liquid; and a piezoelectric actuator plate which is disposed on one of opposite sides of the pressure chamber to close the pressure chamber and is deformed to deliver the liquid through an opening that is disposed on the other of the opposite sides of the pressure chamber to be held in communication with the pressure chamber, and which has a laminated structure including: a piezoelectric layer which is deformable at least in a planar direction thereof by an application of an electric field to the piezoelectric layer; and a planar diaphragm laminated on the piezoelectric layer, wherein a rigidity of the piezoelectric actuator plate is lower at a portion thereof over an inner side of an inner peripheral part of the pressure chamber than at a portion thereof over the inner peripheral part that is located outside the inner side of the inner peripheral part of the pressure chamber.