Patent ID: 7252362

Claim:
A printing apparatus which drives and controls a printhead for discharging a liquid from main nozzles and printing on a printing medium, the printhead having a common liquid chamber which receives a liquid, a plurality of main nozzles which are aligned at a predetermined interval along a longitudinal direction of the common liquid chamber and which are used for printing, a plurality of dummy nozzles which are aligned on two sides of the main nozzles along an array direction of the main nozzles and which are not used for printing, and a plurality of liquid chambers which communicate with the common liquid chamber while the main nozzles and the dummy nozzles communicate with the liquid chambers, comprising: preliminary discharge means for performing preliminary discharge from the main nozzles and the dummy nozzles in order to establish a good discharge state of the liquid from the main nozzles; switching means for alternately switching between the main nozzles and the dummy nozzles; and control means for executing and controlling, as the preliminary discharge performed by said preliminary discharge means, a toggle preliminary discharge operation of alternately performing discharge from the main nozzles and the dummy nozzles every column for a plurality of successive columns.