Patent ID: 8215738

Claim:
A droplet ejection apparatus, comprising: a droplet ejection head which has a plurality of nozzles arrayed two-dimensionally, droplets of liquid being ejected from the nozzles and deposited onto an image-rendering medium to form dots on the image-rendering medium; and a relative movement device which moves the droplet ejection head and the image-rendering medium relatively to each other in a relative movement direction, wherein: the droplet ejection head has a nozzle arrangement in which, out of the plurality of nozzles, a row of nozzles sharing a same liquid supply flow channel is divided into M (where M is an integer greater than one) nozzle group blocks and positions of all of the nozzles within each nozzle group block are shifted in the relative movement direction so as to provide a predetermined positional difference in the relative movement direction to the positions of the nozzles between the M nozzle group blocks, and the nozzle arrangement in which the nozzles are arrayed two-dimensionally is configured such that, between dots formed on the image-rendering medium by adjacent nozzles within a certain one nozzle row, at least one dot formed by a nozzle within another nozzle row is arranged so that the dots formed by the adjacent nozzles within the one nozzle row are arranged with an interval of N (where N is an integer greater than one) dots; the droplet ejection apparatus comprises M ejection drive devices which independently perform ejection control on the respective M nozzle group blocks; and the ejection drive devices carry out ejection drive on the nozzles within the same nozzle group block at ejection timing of a same phase, and also carry out ejection drive on the nozzles in different nozzle group blocks at different ejection timings with a phase difference corresponding to the positional difference.