Patent ID: 7950344

Claim:
A head unit for use in a droplet ejection apparatus, the head unit comprising: a plurality of droplet ejection heads for ejecting a liquid material onto a base, wherein the plurality of droplet ejection heads comprise at least a first droplet ejection head, an additional first droplet ejection head, a second droplet ejection head, an additional second droplet ejection head, a third droplet ejection head, and a fourth droplet ejection head, each including a nozzle array having a plurality of nozzles aligned along a first direction, wherein the first droplet ejection head, the additional first droplet ejection head, the second droplet ejection head, and the additional second droplet ejection head eject the liquid material of a first color, and the third droplet ejection head and the fourth droplet ejection head eject the liquid material of a second color, wherein the first droplet ejection head and the second droplet ejection head are arranged so that a droplet ejected from the nozzle of the nozzle array of the first droplet ejection head and a droplet ejected from the nozzle of the nozzle array of the second droplet ejection head are consecutive via a seam between the first droplet ejection head and the second droplet ejection head when viewed from a second direction perpendicular to the first direction, the additional first droplet ejection head and the additional second droplet ejection head are arranged so that a droplet ejected from the nozzle of the nozzle array of the additional first droplet ejection head and a droplet ejected from the nozzle of the nozzle array of the additional second droplet ejection head are consecutive via a seam between the additional first droplet ejection head and the additional second droplet ejection head when viewed from a second direction perpendicular to the first direction, and the third droplet ejection head and the fourth droplet ejection head are arranged so that a droplet ejected from the nozzle of the nozzle array of the third droplet ejection head and a droplet ejected from the nozzle of the nozzle array of the fourth droplet ejection head are consecutive via a seam between the third droplet ejection head and the fourth droplet ejection head when viewed from the second direction, wherein all the seams are arranged at different positions when viewed from the second direction, and wherein the second droplet ejection head is arranged between the additional first droplet ejection head and the additional second droplet ejection head when viewed from the first direction, and the additional first droplet ejection head is arranged between the first droplet ejection head and the second droplet ejection head when viewed from the first direction.