Line printing type inkjet image forming apparatus and method of enhancing printed image quality

An inkjet image forming apparatus comprising:

• a printhead having a first nozzle row and a second nozzle row respectively including one or more subheads and a length corresponding to a width of a print medium, the one or more subheads each having one or more groups each having a plurality of nozzles arranged in the first nozzle row and the second nozzle row, respectively;
• a driving unit to drive the plurality of nozzles of the one or more subheads to print an image;
• a print medium feeding unit to feed the print medium along a predetermined path in a feeding direction;
• and
• a controller to synchronize operations of the driving unit and the print medium feeding unit so that ink ejected from the plurality of nozzles of the one or more subheads is deposited on a desired portion of the print medium and to generate a first control signal so that the driving unit time-divisionally drives the plurality of nozzles arranged in the first and second nozzle rows and the first and second nozzle rows,
• wherein the controller time-divisionally drives the first and second nozzle rows and the one or more groups in a same direction.

A method of enhancing printed image quality of an inkjet image forming apparatus, the method comprising:

• inputting data to be printed from a host;
• comparing an input resolution with an actual resolution of a printhead;
• feeding a print medium along a first feeding path and time-divisionally driving nozzles of the printhead to print an image on the print medium;
• feeding again the print medium along the first feeding path via a second feeding path if the input resolution is higher than the actual resolution;
• and
• time-divisionally driving the nozzles of the printhead divided into one or more groups to print an image on the print medium.
• wherein an order for the feeding of the print medium and time-divisionally driving the nozzles of the printhead and an order of the time-divisionally driving of the nozzles the printhead divided into the one or more groups are in the same direction.

An image forming apparatus, comprising:

• a data input unit to input data to be printed from a host;
• a feeding unit to feed a print medium;
• a driving unit to time-divisionally drive the printhead;
• and
• a controller to compare an input resolution with an actual resolution of a printhead, to control the feeding unit to feed the print medium along a first feeding path, to control the driving unit to time-divisionally drive nozzles of the printhead to print an image on the print medium, to control the feeding unit to feed again the print medium along the first feeding path via a second feeding path if the input resolution is higher than the actual resolution, and to control the driving unit to time-divisionally drive the nozzles of the printhead divided into one or more groups to print the image on the print medium, wherein an order of time-divisionally driving the nozzles of the printhead and an order of the time-divisionally driving of the nozzles the printhead divided into the one or more groups are in a same direction.

An image forming apparatus comprising:

• a printhead unit including a first subhead having first and second groups having a plurality of first and second nozzles, respectively, and a second subhead having third and fourth groups having a plurality of third and fourth nozzles, respectively;
• a controller to control the printhead units to perform a first printing operation to sequentially eject ink from first and third nozzles in a first direction, and to control the printhead unit to perform a second printing operation to sequentially eject ink from second and fourth nozzles in the second and fourth group in the first direction such that an image is formed through the first and second printing operations;
• and
• a plurality of print medium feeding units to feed the print medium under the printhead unit, and the controller controls the plurality of print medium feeding units to feed the print medium a first time under the printhead unit to perform the first printing operation, and the controller controls the plurality of print medium feeding units to feed the print medium a second time under the printhead unit to perform the second printing operation.