Patent ID: 8096631

Claim:
An ink-jet type image-forming apparatus, comprising: a plurality of recording heads each having a plurality of nozzles for ink ejection, each of the nozzles being provided with a heater element on an inside wall thereof, electric pulses being applied to the heater elements to heat up and to eject ink droplets therefrom; and a delivery mechanism which delivers a recording medium in a delivery direction perpendicular to a row direction in which the nozzles are arranged; wherein different ones of the plurality of recording heads print a plurality of regions on the recording medium adjacently arranged in the delivery direction; the apparatus further comprising: a pulse-applying circuit which applies the electric pulses to the heater elements provided on the plurality of recording heads; and a pulse-changing circuit which causes the pulse-applying circuit to change the electric pulses applied therefrom; wherein the pulse-changing circuit is adapted to cause, in case changing an electric pulse to be applied to the heater elements of all the recording heads from a first electric pulse to a second electric pulse which differs from the first electric pulse, the pulse-applying circuit to apply the second electric pulses to the heater elements of all the recording heads after a prescribed delivery length of regions including a plurality of print regions that are adjacent with each other have been printed with the plurality of recording heads; wherein the pulse-changing circuit causes, in the printing of the prescribed delivery length of regions so as to perform a printing operation, for one of the plurality of prescribed regions, the pulse-applying circuit to apply, to the heater elements of one of the recording heads, the second electric pulse changed from the first electric pulse; and the pulse-changing circuit causes, for the other of the plurality of prescribed regions, the pulse-applying circuit to apply, to the heater elements of the other of the recording heads, the first electric pulse without changing to the second electric pulse; and wherein the plurality of recording heads print first and second print regions within the prescribed delivery length, the first and second regions being alternately placed, the first print region being printed with the second electric pulse applied to the heater elements of the recording heads, and the second print region being printed with the first electric pulse applied to the heater elements of the recording heads.