Patent ID: 8727507

Claim:
An ink jet apparatus comprising: multiple nozzles for ejecting ink; pressure chambers, each of the pressure chambers communicating with each of the nozzles; piezoelectric elements A for applying a pressure to the pressure chambers; partition walls arranged between the pressure chambers; piezoelectric elements B, each of piezoelectric elements B supporting each of the partition walls; and a diaphragm arranged between the partition walls and the piezoelectric elements B, the diaphragm being in contact with the piezoelectric elements A; wherein: a relationship L 4 ≧L 2 >L 1 is satisfied when: L 1 is a width of a first convex part of the diaphragm in direction X along which the nozzles are arranged, the first convex part being in contact with one of the piezoelectric elements A; L 2 is a width of a second convex part of the diaphragm in direction X, the second convex part being in contact with one of the piezoelectric elements B; and L 4 is a width of a part of each of the piezoelectric elements A and the piezoelectric elements B in direction X; and a relationship W 2 >W 1 is satisfied when: W 1 is a width of a part of each of the piezoelectric elements A and the piezoelectric elements B in direction Y perpendicular to direction X and along an axis of each of the nozzles; and W 2 is a width of the first convex part of the diaphragm in direction Y.