Patent ID: 8636344

Claim:
A piezoelectric unit, comprising: a plurality of piezoelectric elements formed along a plurality of slits so as to extend from a first end portion of a piezoelectric element block toward a second end portion thereof; and a circuit board with a driving electrode formed on a surface thereof, wherein the piezoelectric elements each include an active region in which a first internal electrode, a second internal electrode, a piezoelectric material layer interposed between the first internal electrode and the second internal electrode, and an insulative outer layer are stacked, the piezoelectric element block includes an inactive region in which the first internal electrode extending from the active region as far as the second end portion, a first dummy electrode formed on the second end portion at a position along an extension from the second internal electrode toward the second end portion, at least one isolated second dummy electrode formed between the second internal electrode and the first dummy electrode, the piezoelectric material layer, and the outer layer are stacked; a first external electrode connected to the first internal electrode at an end face of the second end portion; and a second external electrode connected to the second internal electrode at an end face of the first end portion, the second internal electrode extending through the active region so as to reach the first end portion, and the first external electrode and the second external electrode are formed so as to reach a surface of the outer layer on one side of the inactive region, and the driving electrode is connected to the first external electrode and the second external electrode located in the inactive region.