Patent ID: 8164792

Claim:
A printing device comprising: a rotationally driving section that rotates a print object; a print head having a plurality of discharge nozzles arranged in a radial direction of a circle traced by the print object being rotated by the rotationally driving section, the print head discharging ink drops at two or more timings from the discharge nozzles; and a controlling section that converts visible information, expressed using biaxial orthogonal coordinate data, into polar coordinate data; binarizes the polar coordinate data to generate binarized polar coordinate data; then, performs landing position correction to correct displacements in landing positions of the ink drops, the displacements being caused by the order in which the ink drops are discharged from the discharge nozzles; generates ink discharge data from the binarized polar coordinate data; and causes the ink drops to be discharged on the basis of the ink discharge data from the print head onto the print object being rotated by the rotationally driving section, wherein when a phase number representing the order in which the ink drop is discharged from each discharge nozzle of the print head is n (n=0, 1, 2, . . . ) and an interval between the timings of discharging the ink drops is Δt(sec), a displacement amount Δj of the landing position of each ink drop corresponding to a dot d at coordinates (i, j) in the binarized polar coordinate data is calculated by the following expression: Δ j=n×Δt×f×T where f is the number of rotations (rps) of the print object, and T is the number of print dots in a direction of rotation.