Patent ID: 6022097
Filing Date: 2000-02-08
Classification: B41J

Abstract:
An ink-jet printer which uses an ink containing fine solid particles of a coloring material suspended in a carrier liquid, comprising:a print head comprising (i) an ink chamber to be filled with said ink, (ii) an ink ejection orifice located at one end of said ink chamber, (iii) a first electrode surrounding said ink chamber to produce an electric field in said ink chamber such that by electrophoresis induced by said electric field, said particles in said ink in said ink chamber are concentrated in the vicinity of said orifice, and (iv) a second electrode which is disposed in said ink chamber and has a tip positioned close to said orifice to produce another electric field to eject at least one agglomeration of said particles together with an amount of said carrier liquid from said orifice; andcontrol means for controlling said print head comprising:first means for applying a first DC voltage to said first electrode and periodically applying a second DC voltage as a pulse to said second electrode based on externally supplied print information,second means for checking an elapsed length of time which has elapsed from a decay of the pulse of said second DC voltage before a rise of a next pulse of said second DC voltage,third means for inverting a polarity of said first DC voltage, andfourth means for storing a first predetermined length of time which is arbitrarily chosen;wherein said second means compares said elapsed length of time with said first predetermined length of time, and when said elapsed length of time checked by said second means is the same or greater than said first predetermined length of time, said polarity of said first DC voltage is inverted.