Patent ID: 7525236

Claim:
A piezoelectric element unit comprising: a piezoelectric element group including an array of piezoelectric elements, each piezoelectric element having an external electrode; a fixing plate to which a portion of the rear surface of the piezoelectric element group is fixed by polymerization such that a end portion of the piezoelectric element group protrudes from an surface of the fixing plate; and a wiring member having a wiring terminal that is bonded to an end portion of the external electrode of each of the piezoelectric elements, wherein the piezoelectric element group has a wiring connection surface located opposite to the surface fixed to the fixing plate, the wiring connection surface having a solder-bonding region and a resist application region, the resist application region being located at a rear end side of the solder-bonding region, wherein when the wiring terminal of the wiring member is soldered to the solder-bonding region, a solder resist applied to the resist application region is melted, and the wiring member is bonded to the wiring connection surface, and wherein the resist application region has an excess-resist application region provided at least at one end of the resist application region which protrudes in the direction that the array of piezoelectric elements are aligned in the piezoelectric element group toward the end portion of the external electrode to which the wiring terminal is connected.