Patent ID: 8714681

Claim:
An inkjet printer comprising: an inkjet head configured to discharge ink from a plurality of nozzles formed in an ink discharging surface thereof, the plurality of nozzles arranged in a plurality of nozzle rows along a first direction, the plurality of nozzle rows arranged along a second direction that is perpendicular to the first direction and parallel to the ink discharging surface; a head moving unit configured to move the inkjet head relative to a recording sheet along the second direction; a wave shape generating mechanism configured to deform the recording sheet in a predetermined wave shape that has top portions of portions protruding in a third direction toward the ink discharging surface and bottom portions of portions recessed in a fourth direction opposite to the third direction, the top portions and the bottom portions alternately arranged along the second direction; a gap variation acquiring device configured to acquire gap variation information related to a variation of a gap between a specific portion of the ink discharging surface and the recording sheet deformed in the predetermined wave shape as a function of a position of the inkjet head in the second direction, the specific portion located within a usage nozzle disposed area of the ink discharging surface where usage nozzle rows to be used in a printing operation, of the plurality of nozzle rows, are disposed; a first determining device configured to determine representative gap variation information related to a variation, as a function of the position of the inkjet head in the second direction, of a representative gap that represents respective gaps between the usage nozzle rows and the recording sheet deformed in the predetermined wave shape, by multiplying the acquired gap variation information by a correction coefficient that is dependent on a width of the usage nozzle disposed area in the second direction and a wavelength of the predetermined wave shape of the recording sheet; and a second determining device configured to determine ink discharging timing to discharge ink from the usage nozzle rows, based on the representative gap variation information determined by the first determining device, under an assumption that the respective gaps between the usage nozzle rows and the recording sheet deformed in the predetermined wave shape are equal to the representative gap.