Liquid droplet ejecting apparatus, liquid droplet ejecting method, and medium storing program for liquid droplet ejecting apparatus

A liquid droplet ejecting apparatus comprising:

• a first head having a plurality of first nozzles, first liquid droplets being ejected from the plurality of first nozzles based on image data;
• a second head having a plurality of second nozzles, second liquid droplets having a same color as a color of the first liquid droplets being ejected from the plurality of second nozzles, based on the image data;
• a conveyor, a printing medium being conveyed by the conveyor in a conveyance direction with respect to the first head and the second head;
• a moving device, the first head and the second head being moved in a movement direction crossing the conveyance direction;
• and
• a controller,
• wherein the first head and the second head are disposed such that positions of first nozzles as a part of the plurality of first nozzles and positions of second nozzles as a part of the plurality of second nozzles overlap with one another in the conveyance direction in a predetermined joint area, and
• the controller is configured to execute:
• a process of obtaining a weight value relevant to a color from the image data with respect to each of pixels;
• a process of dividing the image data into blocks each composed of a plurality of pixels;
• a process of calculating, with respect to each of the blocks, an average value of weight values of pixels, included in the plurality of pixels and composing each of the blocks;
• a process of obtaining a dark area with the average value of the weight values being a threshold value or more, for each printing pass;
• a process of determining whether a part or all of the joint area corresponds to the dark area in a following printing pass to be executed after a preceding printing pass as a predetermined printing pass;
• and
• a process of changing a number of the first nozzles to be used relevant to ejection and a number of the second nozzles to be used relevant to the ejection in the preceding printing pass, in the following printing pass, or in both of the preceding printing pass and the following printing pass such that the part or all of the joint area corresponds to the dark area in the following printing pass, in a case where the part or all of the joint area does not correspond to the dark area.

A liquid droplet ejecting method using a liquid droplet ejecting apparatus, the liquid droplet ejecting apparatus including:

• a first head having a plurality of first nozzles, first liquid droplets being ejected from the plurality of first nozzles based on image data, a second head having a plurality of second nozzles, second liquid droplets having a same color as a color of the first liquid droplets being ejected from the plurality of second nozzles, based on the image data, and a controller, the first head and the second head being disposed such that positions of first nozzles as a part of the plurality of first nozzles and positions of second nozzles as a part of the plurality of second nozzles overlap with one another in a conveyance direction of a printing medium in a predetermined joint area,
• the liquid droplet ejecting method comprising:
• obtaining a dark area from ejection data as data after execution of a half tone process with respect to the image data, the dark area being an area with a total value of volume being a threshold value or more, the total value of volume being a total value of a cumulative volume of the first liquid droplets ejected from a row of the first nozzles aligned in a movement direction crossing the conveyance direction and a cumulative volume of the second liquid droplets ejected from a row of the second nozzles aligned in the movement direction;
• determining whether a part or all of the joint area corresponds to the dark area in a following printing pass to be executed after a preceding printing pass as a predetermined printing pass;
• and
• changing a number of the first nozzles to be used relevant to ejection and a number of the second nozzles to be used relevant to the ejection in the preceding printing pass, in the following printing pass, or in both of the preceding printing pass and the following printing pass such that the part or all of the joint area corresponds to the dark area in the following printing pass, in a case where the part or all of the joint area does not correspond to the dark area.

A non-transitory medium storing a program for a liquid droplet ejecting apparatus, the liquid droplet ejecting apparatus including a first head having a plurality of first nozzles, first liquid droplets being ejected from the plurality of first nozzles based on image data, a second head having a plurality of second nozzles, second liquid droplets having a same color as a color of the first liquid droplets being ejected from the plurality of second nozzles based on the image data, and a controller, the first head and the second head being disposed such that positions of first nozzles as a part of the plurality of first nozzles and positions of second nozzles as a part of the plurality of second nozzles overlap with one another in a conveyance direction of a printing medium in a predetermined joint area,

• the program for the liquid droplet ejecting apparatus causing the controller to execute:
• a process of obtaining a dark area from ejection data as data after execution of a half tone process with respect to the image data, the dark area being an area with a total value of volume being a threshold value or more, the total value of volume being a total value of a cumulative volume of the first liquid droplets ejected from a row of the first nozzles aligned in a movement direction crossing the conveyance direction and a cumulative volume of the second liquid droplets ejected from a row of the second nozzles aligned in the movement direction;
• a process of determining whether a part or all of the joint area corresponds to the dark area in a following printing pass to be executed after a preceding printing pass as a predetermined printing pass;
• and
• a process of changing a number of the first nozzles to be used relevant to ejection and a number of the second nozzles to be used relevant to the ejection in the preceding printing pass, in the following printing pass, or in both of the preceding printing pass and the following printing pass such that the part or all of the joint area corresponds to the dark area in the following printing pass, in a case where the part or all of the joint area does not correspond to the dark area.