Device and method for driving ink jet printing head capable of attaining both high quality printing and reduction of ink consumption

A driving device for an ink jet printing head having at least a plurality of pressure-generation chambers filled with ink, a plurality of nozzles communicating with the pressure-generation chambers, respectively, for discharging the ink, and a plurality of driving means corresponding to the pressure-generation chambers for causing change of pressure in the pressure-generation chambers, utilizing a plurality of driving voltage waveforms for driving the driving means to let various types of ink drops of different amount be discharged from the nozzles onto a recording medium based on a printing mode and printing data, comprising:

• a preliminary waveform generation means for generating a driving voltage waveform used for driving the driving means to the extent that ink drops are not discharged from the nozzles at a discharge break during the printing when ink drops are not supposed to be discharged from the nozzles;
• and
• a purge waveform generation means for generating a driving voltage waveform used for discharging ink inside the nozzles at certain intervals set based on at least one of a temperature and humidity around the ink jet printing head and the amount of ink drops of the smallest size used under a selected printing mode;
• wherein the preliminary waveform generation means and the purge waveform generation means are performed at different times and independently from each other;
• wherein the preliminary waveform generation means can be performed while the ink jet printing head is scanning, the preliminary waveform generation means for vibrating a meniscus of the ink in each of the nozzles to the extent that ink drops are not discharged from the nozzles, churning the ink of increased viscosity, and decreasing an influence of the increased viscosity;
• and
• wherein the purge waveform generation means is performed while the ink jet printing head is outside of a print region, the purge waveform generation means for emitting the ink of increased viscosity and refreshing the ink in the pressure-generation chambers.