Patent ID: 7470004

Claim:
A liquid ejection unit comprising: a heating element disposed on a substrate; a nozzle layer through which a nozzle located over the heating element is formed; a barrier layer interposed between the substrate and the nozzle layer; a liquid chamber formed by a part of the barrier layer and having a pair of walls confronting each other with the heating element therebetween; a pair of individual flow paths formed by extending the pair of walls of the liquid chamber and disposed on both the sides of the liquid chamber so as to communicate with the liquid chamber, wherein a liquid is supplied to the liquid chamber from at least one of the pair of individual flow paths, and a distance U between the pair of walls in the liquid chamber and the flow path width W of the individual flow paths is set to satisfy the relation U>W; a plurality of the heating elements are arranged on the substrate in one direction; the liquid chamber and the pair of individual flow paths are disposed in correspondence with each of the heating elements; and the pair of individual flow paths are formed to extend in a direction perpendicular to a direction in which adjacent heating elements are arranged; wherein the pair of individual flow paths comprises: a first individual flow path connecting to a common flow path; and a second individual flow path extending in a direction opposite to the first individual flow path across the liquid chamber, wherein the second individual flow paths of at least two adjacent liquid chambers communicate with each other; the liquid chambers are disposed at a disposing pitch P; and a distance between a first line, which connects centers of the liquid chambers in the direction of the disposing pitch, and a second line which is parallel to the first line and in contact with a wall portion that is farthest from the first line and which is a boundary of the second individual flow paths satisfies the following relation L≦ 2 ×P.