| 摘要 |
In a method of driving a plurality of ink jet heads, each ink jet head comprises a plurality of ink chambers that are each provided with an ink nozzle. The ink nozzles of each of the ink jet heads are divided into N sets each including every N-th ink nozzle, where N is an integer of two or more, and the N sets of the ink nozzles are arranged in parallel longitudinal rows in a staggered arrangement. The respective ink nozzles in corresponding rows of the ink jet heads are spaced apart from each other by a distance equal to an integral multiple of a pitch of the rows of the ink nozzles in each of the ink jet heads in a sub-scanning direction in which a recording medium is moved, and the ink nozzles eject ink as the ink nozzles move relative to the recording medium in a main scanning direction perpendicular to the sub-scanning direction. The ink nozzles of each of the N sets are driven to eject ink on a same line on the recording medium, by controlling a timing at which the ink nozzles of each set are driven and a relative speed between the ink jet heads and the recording medium. When an amount of misalignment between dots recorded by a reference set of the ink nozzles and dots recorded by another set of the ink nozzles exceeds one-half of a dot pitch defined in the sub-scanning direction, an order in which the sets of ink nozzles are driven is changed to reduce the amount of misalignment between dots to below one-half of the dot pitch defined in the sub-scanning direction.
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