Patent attributes
A waveform signal output circuit selectively outputs, to an ejection energy applier, either one of a first waveform signal so as to make an ink droplet ejected from a nozzle and a second waveform signal so as not to make an ink droplet ejected from the nozzle. A continuous non-ejection counter counts a continuous non-ejection number. A ejection history memory stores therein an ejection history. A non-ejection frequency detector detects a non-ejection frequency. A thickening degree determiner determines a thickening degree of ink in the nozzle. A waveform signal selector makes the waveform signal output circuit output the second waveform signal to the ejection energy applier when an ink droplet is not ejected in the current printing cycle and in addition a thickening degree is equal to or greater than a predetermined value.
