Ink jet printing apparatus and preliminary ink ejection method

An ink jet printing apparatus for forming an image by ejecting ink from a print head onto a print medium, wherein the print head has arrayed in nozzle columns at least a plurality of large nozzles and a plurality of small nozzles, each of the large nozzles ejecting a larger volume of ink per single ejection than each of the small nozzles ejects per single ejection, and the large nozzles and small nozzles eject ink supplied from a common ink chamber, the ink jet printing apparatus comprising:

• preliminary ejection means for performing ink ejections, not involved in the formation of an image, from the nozzles of the print head;
• suction means for sucking out ink from the print head through the nozzles of the print head;
• and
• control means for causing said suction means to suck out ink from the print head and then causing said preliminary ejection means to perform the ink ejections,
• wherein, in an ink ejection operation by said preliminary ejection means following the suction of ink by said suction means, said control means causes the nozzles of the same size to eject ink simultaneously and controls to set a frequency at which to eject ink from the small nozzles to be lower than a frequency at which to eject ink from the large nozzles.

A preliminary ink ejection method using an ink jet printing apparatus, wherein the ink jet printing apparatus forms an image by ejecting ink from a print head onto a print medium, wherein the print head has arrayed in nozzle columns at least a plurality of large nozzles and a plurality of small nozzles, each of the large nozzles ejecting a larger volume of ink per single ejection than each of the small nozzles ejects per single ejection, and the large nozzles and small nozzles eject ink supplied from a common ink chamber, the preliminary ink ejection method comprising:

• a preliminary ejection step of performing ink ejections, not involved in the formation of an image, from the nozzles of the print head;
• a suction step of sucking out ink from the print head through the nozzles of the print head;
• and
• a control step of causing said suction step to suck out ink from the print head and then causing said preliminary ejection step to perform the ink ejections,
• wherein, in an ink ejection operation in said preliminary ejection step following the suction of ink in said suction step, said control step causes the nozzles of the same size to eject ink simultaneously and controls to set the number of ejections from the large nozzles to be greater than the number of ejections from the small nozzles.

A preliminary ink ejection method using an ink jet printing apparatus, wherein the ink jet printing apparatus forms an image by ejecting ink from a print head onto a print medium, wherein the print head has arrayed in nozzle columns at least a plurality of large nozzles and a plurality of small nozzles, each of the large nozzles ejecting a larger volume of ink per single ejection than each of the small nozzles ejects per single ejection, and the large nozzles and small nozzles eject ink supplied from a common ink chamber, the preliminary ink ejection method comprising:

• a preliminary ejection step of performing ink ejections, not involved in the formation of an image, from the nozzles of the print head;
• a suction step of sucking out ink from the print head through the nozzles of the print head;
• and
• a control step of causing said suction step to suck out ink from the print head and then causing said preliminary ejection step to perform the ink ejections,
• wherein, in an ink ejection operation in said preliminary ejection step following the suction of ink in said suction step, said control step causes the nozzles of the same size to eject ink simultaneously and controls to set a frequency at which to eject ink from the small nozzles to be lower than a frequency at which to eject ink from the large nozzles.