After printing based on each job is ended, a printing control unit controls an operation of a printing unit so that an inspection pattern is printed on a print sheet in a period during which a conveyance control unit is keeping a conveyance speed of a print sheet at a constant speed. A maintenance content determination unit determines a maintenance content for the printing unit on the basis of an inspection result obtained by inspecting a print image for the inspection pattern. The printing control unit controls operations of the printing unit and a cleaning mechanism depending on the maintenance content determined by the maintenance content determination unit.

A multi-color printer has an array of monochrome fixed inkjet printheads aligned in a media feed direction. The printer includes: a first printhead positioned furthest upstream relative to the media feed direction; a second printhead positioned furthest downstream relative to the media feed direction; and a third printhead positioned between the first and second printheads. Each printhead is supplied with a respective ink from a multi-color ink set, the first printhead being supplied with a lowest luminance ink of the ink set and the third printhead being supplied with a highest luminance ink of the ink set.

A liquid ejection apparatus includes: a plurality of nozzles configured to eject liquid onto a conveyed object conveyed by a conveyance unit, based on input image data; and a control unit configured to control a number of droplets in first flushing for ejecting the liquid outside a region corresponding to the image data and a number of droplets in second flushing for ejecting the liquid inside the region corresponding to the image data in addition to ejection based on the image data. The control unit is configured to control the number of droplets in the first flushing and the number of droplets in the second flushing based on at least a length of the image data in a direction in which the conveyed object is conveyed.

In ejecting ink from unused ink ejection ports or ink ejection ports not used frequently onto a can body to suppress ink clogging, the ink clogging is suppressed while degradation in the quality of an image to be formed on the can body is suppressed. On the surface of a can main body 110, a main image MG, which is a main image, and a strip-shaped image OG, which is a sub-image, are formed. The strip-shaped image OG is formed using ink ejection ports not used at forming the main image MG or low-frequency ink ejection ports not ejecting ink frequently. Thus, ink clogging hardly occurs in an ink jet head.

In the method for controlling actuators, corresponding actuators are controlled so that they eject the ink droplets for the print image. Corresponding actuators are additionally controlled in order to eject refresh droplets in the image background according to a random distribution. In the event that no image droplet is printed between two successive refresh droplets, the ink meniscus is set into vibration as a refresh measure between the refresh droplets.

A control unit 6 of a printer 1 determines the combination of conditions of regular flushing that ejects ink into a maintenance unit 5, and onto-paper flushing that ejects ink onto printing paper P, based on the set print mode. To achieve the dot density defined by the selected combination, flushing dots Df are added to the input data 10 to be printed and are printed. When printing, regular flushing is executed at the frequency and strength determined by the selected combination of conditions.

A printing system, print control device, and print control method enable non-technical users without specific technical knowledge to appropriately set the flushing conditions of a printer. A host that sends commands to an inkjet printer that prints on a print medium provides a user interface for selecting an operating mode prioritizing the throughput of the printing operation, or a normal operating mode. When the operating mode prioritizing printer throughput is selected using the user interface, the host generates a command setting a condition for flushing the ink nozzles of the inkjet printer, and sends the generated command to the inkjet printer.

In an embodiment, a method of maintaining nozzles in a print-ready condition includes determining image content to be printed in an upcoming print swath, and for each ink color present within the image content, constructing an inked portion of an associated spit bar adjacent to the upcoming print swath to include the present ink color. For each ink color not present within the image content, an empty portion of an associated spit bar is constructed adjacent to the upcoming print swath.

A controller controls printing heads to print a page information mark with black ink to perform line flushing. The printing heads each have a plurality of inkjet nozzles for discharging ink being disposed in parallel in a width direction of web paper. Upon printing the mark, when an overlap region is present in which a mark printable region overlaps a line flushing region with ink other than the black ink, the controller performs control to decrease an ink discharge amount per unit area in the overlap region in the mark printable region to be smaller than that in the mark printable region except for the overlap region and the line flushing region. This causes a decreased total ink discharge amount in the overlap region.

A liquid ejection apparatus includes: a plurality of nozzles configured to eject liquid onto a conveyed object conveyed by a conveyance unit, based on input image data; and a control unit configured to control a number of droplets in first flushing for ejecting the liquid outside a region corresponding to the image data and a number of droplets in second flushing for ejecting the liquid inside the region corresponding to the image data in addition to ejection based on the image data. The control unit is configured to control the number of droplets in the first flushing and the number of droplets in the second flushing based on at least a length of the image data in a direction in which the conveyed object is conveyed.