Patent ID: 8894173

Claim:
A method for acquiring a deviation value between an ink landing position of an ink droplet discharged from an inkjet head of an inkjet printer moving toward a first side along a scanning direction and an ink landing position of an ink droplet discharged from the inkjet head moving toward a second side opposite to the first side along the scanning direction, for each of different moving velocities of the inkjet head, the inkjet printer configured to perform printing on a recording sheet by discharging ink droplets from nozzles formed in an ink discharge surface of the inkjet head while reciprocating the inkjet head relative to the recording sheet along the scanning direction parallel to the ink discharge surface, the method comprising: a first pattern printing step of printing a first pattern over a first range of the recording sheet in the scanning direction, by discharging ink droplets from the nozzles while reciprocating the inkjet head at a first moving velocity along the scanning direction, the first pattern being a pattern for acquiring a first deviation value that is the deviation value of the ink landing positions in the first range when the inkjet head moves at the first moving velocity; a second pattern printing step of printing a second pattern over a second range of the recording sheet in the scanning direction, the second range being included in and shorter than the first range in the scanning direction, by discharging ink droplets from the nozzles while reciprocating the inkjet head at a second moving velocity different from the first velocity along the scanning direction, the second pattern being a pattern for acquiring a second deviation value that is the deviation value of the ink landing positions in the second rangewhen range when the inkjet head moves at the second moving velocity; a first deviation acquiring step of acquiring, from the first pattern, the first deviation value in each of a plurality of positions in the first range; a variation acquiring step of acquiring variation information that represents a variation in the scanning direction of the first deviation value acquired in each of the plurality of positions in the first range; a first representative value acquiring step of acquiring, from the variation information, a first representative value that represents the first deviation value acquired in each of the plurality of positions in the first range; a second deviation acquiring step of acquiring the second deviation value from the second pattern; and a second representative value acquiring step of acquiring a second representative value that represents the deviation value of the ink landing positions in the first range when the inkjet head moves at the second moving velocity, based on the second deviation value and a difference between the first representative value and the first deviation value acquired in the second range included in the first range.