Patent ID: 7997672
Filing Date: 2011-08-16
Classification: B41J

Abstract:
1. An inkjet recording apparatus comprising: a conveyance mechanism which conveys a recording medium; a passage unit including therein a plurality of individual ink passages each of which leads from an outlet of a common ink chamber through a pressure chamber to a nozzle; an ejection energy applier which gives ejection energy to ink in a plurality of the pressure chambers of the passage unit, the applier including a plurality of individual electrodes related to the respective pressure chambers; a waveform outputting circuit which outputs to each individual electrode one of a plurality of ejection signals and a flushing signal selected in order in each printing cycle, which is defined by a time period necessary for conveying the printing medium by unit distance corresponding to a printing resolution of an image to be formed on the recording medium, the plurality of ejection signals containing the different numbers of voltage pulses to drive the ejection energy applier, the numbers of voltage pulses corresponding to a plurality of amounts of ink to be ejected from each nozzle in one printing cycle, respectively, the flushing signal containing a plurality of voltage pulses each having a width smaller than that of any voltage pulse containing in the ejection signals, and arranged at smaller intervals than a plurality of voltage pulses containing in any ejection signals so that any nozzle does not eject an ink droplet; a power supply unit which supplies power to the waveform outputting circuit; and a current restricting circuit which restricts a current to flow from the power supply unit into the waveform outputting circuit so that the value of the current to flow from the power supply unit into the waveform outputting circuit is not more than an upper limit current value which has been determined so as to exceed a value of the current to flow from the power supply unit into the waveform outputting circuit when the waveform outputting circuit outputs to all individual electrodes an ejection signal corresponding to the largest amount of ink to eject, and so as to be less than a value of the current to flow from the power supply unit into the waveform outputting circuit when the waveform outputting circuit outputs, to all individual electrodes, the flushing signal, whose voltage pulse level is equal to that of the ejection signals, wherein the power consumed by the waveform outputting circuit when the waveform outputting circuit outputs the flushing signal to all individual electrodes, is higher than the power consumed by the waveform outputting circuit when the waveform outputting circuit outputs, to all individual electrodes, an ejection signal whose voltage pulse level is equal to that of the flushing signal, the ejection signal corresponding to the largest amount of ejected ink, and the current restricting circuit never restricts the current to flow from the power supply unit to the waveform outputting circuit, when the waveform outputting circuit outputs to all the individual electrodes the ejection signal corresponding to the largest amount of ejected ink, and restricts the current to flow from the power supply unit to the waveform outputting circuit, to a value not more than the upper limit current value, when the waveform outputting circuit outputs the flushing signal to all the individual electrodes.