Patent ID: 7731332

Claim:
An ejection head, comprising: n (where n is an integer not less than 2) ejection aperture groups arranged in a sub-scanning direction, each of the groups including ejection aperture rows arranged at prescribed intervals in a main scanning direction, each of the ejection aperture rows including a plurality of ejection apertures aligned in an oblique direction with a prescribed angle θ (where 0<θ<90°) with respect to the main scanning direction, wherein: ejection apertures for a row in a first ejection aperture group are phase offset in the main scanning direction relative to ejection apertures in said row for a second ejection aperture group, such that along said main scanning direction, ejection apertures of the first ejection aperture group alternate with ejection apertures of the second ejection aperture group; n is an even number; a pitch between the ejection apertures in the sub-scanning direction is greater than other pitches between other ejection apertures; and the ejection aperture groups are arranged at different phases in the main scanning direction, in such a manner that, pitches between return positions projected to align in the main scanning direction are uniform, where return positions are boundaries between the ejection aperture rows arranged adjacently in the main scanning direction of the ejection aperture rows in the ejection aperture groups.