Patent ID: 8240819

Claim:
An ink jet head comprising: a piezoelectric element including a plurality of partition walls arranged at intervals, and a plurality of pressure chambers which are provided between neighboring ones of the partition walls and to which ink is supplied; a nozzle plate including a plurality of nozzles which discharge the ink, the nozzles being formed by radiating a laser beam on the nozzle plate; an adhesive which adheres the nozzle plate to the partition walls of the piezoelectric element such that the nozzles communicate with the pressure chambers; an electrode provided on a surface of the partition wall facing the pressure chamber, the electrode being configured to deform, when supplied with a driving pulse, the partition walls, thereby pressurizing the ink that is supplied to the pressure chamber and discharging the ink from the nozzle; a first protection film which covers the electrode and is formed of an inorganic material having electrical insulation properties; and a second protection film which is stacked on the first protection film, is exposed to the pressure chamber, and is formed of an organic material having electrical insulation properties, wherein the adhesive includes an excess portion which protrudes into the pressure chamber from between the nozzle plate and the partition wall, and a cut portion which is provided at the excess portion along a direction of radiation of the laser beam, and the second protection film includes a damage hole at an area on which the laser beam is made incident, the second protection film being removed from the damage hole, the first protection film is exposed to an inside of the pressure chamber at a position corresponding to the damage hole, at least a part of the first protection film, which corresponds to the damage hole, has a film thickness of 0.1 μm to 0.5 μm, and the first protection film has a refractive index of 1.1 to 2.0.