Inkjet printing apparatus for changing a range of used ejection ports according to ejection port usage

An inkjet printing apparatus comprising:

• a plurality of print heads each including an ejection port array comprising a plurality of ejection ports arranged in a crossing direction, crossing a conveyance direction of a print medium, and a plurality of elements configured to generate heat to eject ink, the plurality of print heads are constructed to eject ink from the plurality of ejection ports by use of heat generated by the plurality of elements,
• wherein the plurality of print heads include a first print head constructed to eject a first ink of first color and a second print head constructed to eject a second ink of a second color that is a different color from the first color,
• wherein the first print head and the second print head are arranged in the conveyance direction, and
• wherein kogation by heat occurs more easily in the first ink than the second ink, the kogation causing a degree of variation of an amount of first ink ejected by the first print head with respect to a predetermined accumulative ejection amount for the first print head to be larger than a degree of variation of an amount of second ink ejected by the second print head with respect to the predetermined accumulative ejection amount for the second print head;
• and
• a print control unit configured to cause the first print head and the second print head to print an image on a print medium using ejection ports of the first print head and the second print head located within a common predetermined range in the crossing direction, while the print medium is conveyed in the conveyance direction,
• wherein the print control unit is further configured to acquire information about an accumulative ink ejection number for the first print head and an accumulative ink ejection number for the second print head, and
• wherein in a case where (i) the accumulative ink ejection number for the first print head, indicated by the acquired information, is larger than a first threshold of ink ejection number set for the first print head, the first threshold of ink ejection number being set based on the degree of variation of an amount of first ink ejected by the first print head, the print control unit changes the common predetermined range based on the acquired information and in a case where (ii) the accumulative ink ejection number for the first print head, indicated by the acquired information, is not larger than the first threshold of ink ejection number set for the first print head and the accumulative ink ejection number for the second print head, indicated by the acquired information is greater than a second threshold of ink ejection number set for the second print head, the second threshold of ink ejection number being set based on the degree of variation of an amount of second ink ejected by the second print head, the print control unit changes the common predetermined range based on the acquired information, wherein the first threshold of ink ejection number is smaller than the second threshold of ink ejection number.

An inkjet printing apparatus comprising:

• a plurality of print heads each including an ejection port array comprising a plurality of ejection ports arranged in a crossing direction, crossing a conveyance direction of a print medium, the plurality of print heads are constructed to eject ink from the ejection ports,
• wherein the plurality of print heads include a first print head constructed to eject a first ink of first color and a second print head constructed to eject a second ink of a second color that is a different color from the first color,
• wherein the first print head and the second print head are arranged in the conveyance direction, and
• wherein a degree of variation of an amount of first ink ejected by the first print head with respect to a predetermined accumulative ejection amount for the first print head is larger than a degree of variation of an amount of ink ejected by the second print head with respect to a predetermined accumulative ejection amount for the second print head;
• and
• a print control unit configured to cause the first print head and the second print head to print an image on a print medium using ejection ports of the first print head and the second print head located within a common predetermined range in the crossing direction, while the print medium is conveyed in the conveyance direction,
• wherein the print control unit is further configured to acquire information about an accumulative ink ejection number for the first print head and an accumulative ink ejection number for the second print head, and
• wherein the print control unit performs a judgment on whether the accumulative ink ejection number in the first print head is greater than or not greater than the threshold set for the first print head, and in a case where (i) it is judged that the accumulative ink ejection number for the first print head, indicated by the acquired information, is larger than a first threshold of ink ejection number set for the first print head, the first threshold of ink ejection number being set based on the degree of variation of an amount of first ink ejected by the first print head, the print control unit determines to change the common predetermined range based on the acquired information, and in a case where (ii) it is judged that the accumulative ink ejection number for the first print head, indicated by the acquired information, is not greater than the first threshold of ink ejection number set for the first print head, the print control unit performs a judgment on whether the accumulative ink ejection number in the second print head is greater than or not greater than the second threshold of ink ejection number set for the second print head.