US Patent 7862145 Printing apparatus and method of controlling the same

An object of this invention is to properly prevent clogging of each nozzle in order to stably discharge ink without increasing a circuit scale even when the number of nozzles increases. For this purpose, the number of ink discharges from each printing element is stored in a memory. The number of ink discharges from each printing element that is measured from input printing data is subtracted from that stored in the memory, and the subtraction result is rewritten into the memory. The subtraction result is checked in a predetermined period, and if the number of ink discharges from each printing element is equal to or larger than a predetermined count, preliminary discharge to be performed periodically is suppressed.