Patent ID: 7566119

Claim:
An inkjet printhead comprising a cavity unit formed by laminating a plurality of plates which include a first plate having a plurality of through-holes and a second plate, the first plate and second plate being interposed between other plates of the plurality of plates, the cavity unit having: a common ink chamber accommodating ink; a plurality of pressure chambers to which the ink is distributed from the common ink chamber; a plurality of nozzles which are communicated with the respective pressure chambers, and through each of which a droplet of the ink is ejected; and a plurality of connecting passages connecting the common ink chamber with the respective pressure chambers, a part of each of the connecting passages being constituted by a groove formed along one surface of the first plate and open in the one surface, an open end of the groove being covered by the second plate, and one of opposite ends of the groove being connected to the through-hole, the groove including: an orifice portion at which a cross-sectional area of the connecting passage as taken in a direction perpendicular to a direction of flow of the ink is minimized in the connecting passage; and an enlarged portion continuously interposed between an end of the orifice portion and an open end portion of the through-hole, the cross-sectional area of the connecting passage being larger at the enlarged portion than at the orifice portion; wherein the connecting passage further comprises a connecting hole formed through the second plate and in communication with the other end of the groove which end takes the form of a recessed portion opposed to the connecting hole, the cross-sectional area of the connecting passage as taken in the direction perpendicular to the direction of the ink flow being larger at the recessed portion than at the orifice portion, and the orifice portion being disposed between the recessed portion and the enlarged portion.