Patent ID: 6974201

Claim:
An inkjet printing apparatus having plural full-line type inkjet printheads each having an array of printing elements corresponding to a width of a print medium, comprising: control means for, when print data is received, simultaneously performing print-output of said print data by said printhead within a printing area of said print medium and preliminary discharge from said printhead without said printing area of said print medium; driving electric-power calculation means for calculating driving electric power to simultaneously perform said print-output of said print data and said preliminary discharge, by a predetermined length in a conveyance direction of said print medium; determination means for determining whether or not said calculated driving electric power is greater than a threshold value indicating an upper limit of driving electric power to simultaneously perform said print-output of the print data and said preliminary discharge, wherein if said calculated driving electric power is greater than said threshold value, said control means reduces electric power supplied to said printhead to a value less than said threshold value and changes a driving frequency to said printhead; and driving frequency selection means for selecting a predetermined driving frequency from a previously set driving frequency table, wherein said control means controls said driving frequency selection means to select a driving frequency to obtain driving electric power less than said threshold value from said driving frequency table.