Patent ID: 8820889

Claim:
A maintenance method of a liquid ejection head including a nozzle forming surface where a plurality of nozzles are two-dimensionally arranged, each of the nozzles having a quadrangular planar shape including four corners, each of the four corners having two sides and an angle between the two sides, the maintenance method comprising the step of causing a relative movement of a sweep member and the liquid ejection head so as to sweep the nozzle forming surface of the liquid ejection head with the sweep member in such a manner that the sweep member is relatively moved in a sweeping direction, wherein the sweeping direction is determined such that: the sweeping direction makes a non-zero angle within π/8 radian with respect to an extending direction in which one of the two sides forming one of the four corners of each of the nozzles extends, the sweep member passing the one of the four corners last among the four corners of each of the nozzles in the relative movement of the sweep member and the liquid ejection head, the extending direction being oblique to both a lengthwise direction and a breadthwise direction of the liquid ejection head; the sweeping direction satisfies P D ≧D, where P D is a distance between centers of two of the nozzles which are adjacent to each other on a same column in a direction perpendicular to the sweeping direction, and D is a dimension of each of the nozzles taken in the direction perpendicular to the sweeping direction; and if the sweeping direction does not satisfy P D ≧D, then the sweeping direction satisfies P D >D/2, wherein one of two diagonals of the quadrangular planar shape of each of the nozzles is parallel to the lengthwise direction of the liquid ejection head, and the other of the two diagonals is parallel to the breadthwise direction of the liquid ejection head.