Printing apparatus and driving method therefor

A printing apparatus including an inkjet printhead with at least two nozzle arrays arranged in a first direction, each nozzle array including a plurality of nozzles arranged along a second direction intersecting the first direction, the apparatus comprising:

• a conveying unit configured to convey a longitudinally long-shaped sheet in the first direction;
• a driving unit configured to drive the printhead so that each nozzle performs preliminary discharge on the sheet conveyed by the conveying unit while printing a dot based on print data;
• and
• a unit that performs the following operations:
• a first operation of expanding image data onto a memory in correspondence with the first and second directions,
• for each nozzle array of every column data corresponding to the second direction in the expanded image data, a second operation of selecting some of the plurality of nozzles as non-driving nozzles that do not overlap between the nozzle arrays in the first direction, and selecting the remaining nozzles of the plurality of nozzles as driving nozzles,
• a third operation of determining image data of the expanded image data to be assigned to each nozzle array so that each column data indicating driving of a nozzle is assigned only to a nozzle array to which the driving nozzle belongs or to another nozzle array different from a nozzle array to which the non-driving nozzle belongs when the column data corresponds to a non-driving nozzle,
• a fourth operation of generating data for preliminary discharge corresponding to the image data determined in the third operation to discretely perform preliminary discharge by the plurality of nozzles on the sheet in at least one of the first and second directions, by setting the column data as data for the nozzle to perform preliminary discharge when the nozzle selected as the driving nozzle for column data is set as a preliminary discharge target, and another column data which is different from the column data and in which the nozzle is selected as the driving nozzle in the second operation, as data used by the nozzle to perform preliminary discharge when the nozzle selected as the non-driving nozzle for column data is set as a preliminary discharge target, and
• a fifth operation of generating print data by a logical sum of the image data determined in the third operation and the data for preliminary discharge generated in the fourth operation, and outputting the generated print data to each nozzle array.