Conventional inkjet printers print on recording paper by ejecting ink from a print head having a plurality of ink ejection openings or nozzles formed therein. In this inkjet printer, ink ejection problems can occur when air bubbles are generated in the ink while the print head is in use, when ink or microparticles of foreign matter are deposited on the surface of the ink ejection openings, and the like. Further, if the printer is left unused for a long period of time, the ink ejection openings may become clogged with ink, leading to ink ejection problems. Since printing quality suffers if a printing operation is performed while ink ejection is problematic, a purge process is generally performed to restore the ink ejection openings to a good ejection state. The purge process is performed, for example, by generating a negative pressure with a pump to draw ink out of the print head after hermetically sealing the print head with a suction cap, or performing a preliminary ejection process to eject ink from the nozzles. By executing such a purge process, it is possible to restore the ink ejection state, as disclosed in U.S. Pat. No. 6,386,677B1, for example.
USPTO Backgrounds
USPTO Backgrounds