Patent ID: 7628469

Claim:
An ink jet head comprising: a plurality of energy generating elements for generating energy for ejecting ink droplets; a substrate including an ink supply port extending in a direction, said energy generating elements arranged on both sides of said ink supply port; a plurality of ink ejection outlets provided corresponding to said energy generating elements, said ink ejection outlets including an array of large ink ejection outlets for ejecting a relatively large ejection amount of ink, the array of large ink ejection outlets being disposed at one side with respect to said ink supply port, and an array of small ink ejection outlets for ejecting a relatively small ejection amount of ink, the array of small ink ejection outlets being disposed at another side with respect to said supply port; an ejection outlet plate portion provided on said substrate so as to be opposed to said ink supply port; a plurality of ink flow paths for fluid communication between said ink supply port and said ink ejection outlets, respectively; a beam-like projection projected from said ejection outlet plate portion toward said ink supply port so as to oppose said ink supply port, wherein said beam-like projection extends in a longitudinal direction of said supply port; and reinforcing ribs integral with said beam-like projection, wherein said reinforcing ribs extend from said beam-like projection toward the array of large ink ejection outlets and contact said substrate, and said reinforcing ribs are provided only at the one side with respect to said ink supply port.