Patent ID: 8002385
Filing Date: 2011-08-23
Classification: B41J

Abstract:
1. A head unit for use in a droplet ejection apparatus, the head unit being provided with a plurality of droplet ejection heads for ejecting a some kinds of liquid materials each having a predetermined color onto a base in the form of droplets, and the predetermined color including a first color and a second color, wherein the head unit includes at least first and second groups corresponding to the liquid materials of the first and second colors, respectively, wherein the first group includes the plurality of droplet ejection heads comprising at least a first droplet ejection head, a second droplet ejection head, a third droplet ejection head and a fourth droplet ejection head for ejecting the liquid material of the first color, each of the first to fourth droplet ejection heads including first and second nozzle arrays each having a plurality of nozzles linearly aligned along a first direction with a predetermined pitch, and the liquid material of the first color being configured to be ejected through the plurality of nozzles of each of the first to fourth droplet ejection heads in the form of droplets, wherein the second group includes the plurality of droplet ejection heads comprising at least a fifth droplet ejection head, a sixth droplet ejection head, a seventh droplet ejection head and an eighth droplet ejection head for ejecting the liquid material of the second color, each of the fifth to eighth droplet ejection heads including first and second nozzle arrays each having a plurality of nozzles linearly aligned along the first direction with the predetermined pitch, and the liquid material of the second color being configured to be ejected through the plurality of nozzles of each of the fifth to eighth droplet ejection heads in the form of droplets, wherein the first droplet ejection head and the second droplet ejection head are arranged along the first direction so that the nozzles of each of the first and second nozzle arrays of the first droplet ejection head and the nozzles of each of the first and second nozzle arrays of the second droplet ejection head are consecutive with the predetermined pitch 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, and the third droplet ejection head and the fourth droplet ejection head are arranged along the first direction so that the nozzles of each of the first and second nozzle arrays of the third droplet ejection head and the nozzles of each of the first and second nozzle arrays of the fourth droplet ejection head are consecutive with the predetermined pitch via a seam between the third droplet ejection head and the fourth droplet ejection head when viewed from the second direction, and wherein the fifth droplet ejection head and the sixth droplet ejection head are arranged along the first direction so that the nozzles of each of the first and second nozzle arrays of the fifth droplet ejection head and the nozzles of each of the first and second nozzle arrays of the sixth droplet ejection head are consecutive with the predetermined pitch via a seam between the fifth droplet ejection head and the sixth droplet ejection head when viewed from the second direction, and the seventh droplet ejection head and the eighth droplet ejection head are arranged along the first direction so that the nozzles of each of the first and second nozzle arrays of the seventh droplet ejection head and the nozzles of each of the first and second nozzle arrays of the eighth droplet ejection head are consecutive with the predetermined pitch via a seam between the seventh droplet ejection head and the eighth droplet ejection head when viewed from the second direction, wherein the first to eighth droplet ejection heads are arranged so that all the seams thereof are shifted with respect to each other in the first direction when viewed from the second direction, wherein in each of the first to eighth droplet ejection heads the first and second nozzle arrays are arranged in a side by side relation in the second direction and the nozzles of the first nozzle array are shifted with a half pitch in the first direction with respect to the nozzles of the second nozzle array when viewed from the second direction, wherein, when viewed from the second direction, the first and second nozzle arrays of the first droplet ejection head partially overlap the first and second nozzle arrays of the third droplet ejection head, the first and second nozzle arrays of the second droplet ejection head partially overlap the first and second nozzle arrays of the fourth droplet ejection head, the first and second nozzle arrays of the fifth droplet ejection head partially overlap the first and second nozzle arrays of the seventh droplet ejection head, and the first and second nozzle arrays of the sixth droplet ejection head partially overlap the first and second nozzle arrays of the eighth droplet ejection head, wherein the nozzles of the first and second nozzle arrays of the first to fourth droplet ejection heads are arranged so as not to overlap with each other when viewed from the second direction, and the nozzles of the first and second nozzle arrays of the fifth to eighth droplet ejection heads are arranged so as not to overlap with each other when viewed from the second direction, wherein the second droplet ejection head is arranged between the third droplet ejection head and the fourth droplet ejection head when viewed from the first direction, and the third droplet ejection head is arranged between the first droplet ejection head and the second droplet ejection head when viewed from the first direction, the sixth droplet ejection head is arranged between the seventh droplet ejection head and the eighth droplet ejection head when viewed from the first direction, and the seventh droplet ejection head is arranged between the fifth droplet ejection head and the sixth droplet ejection head when viewed from the first direction, wherein the first, second, fourth, fifth, seventh and eighth droplet ejection heads partially overlap each other when viewed from the second direction.