CROSS-REFERENCE TO RELATED APPLICATIONS

This application relates to and claims priority rights from Japanese Patent Application No. 2019-155079, filed on Aug. 27, 2019, the entire disclosures of which are hereby incorporated by reference herein.

BACKGROUND

1. Field of the Present Disclosure

The present disclosure relates to an image forming apparatus.

2. Description of the Related Art

An inkjet-type image forming apparatus performs on-sheet preliminary ink ejection in order to restrain a trouble such as precision deterioration of an ink droplet hitting position and/or ink density deterioration with regard to a nozzle that ejects no ink during predetermined time. The on-sheet preliminary ink ejection is preliminary ink ejection performed (a) when an image specified by a user is printed and (b) on a paper sheet on which the image is printed.

Meanwhile, in case of commercial printing, for example, other than a user image, a post processing object may be printed such as a trim mark that specifies a cutting position for a cutting process or a color patch for evaluation of color reproductivity. In such a case, when the aforementioned on-sheet preliminary ink ejection is performed, if the ink droplet is ejected on the post processing object, then the postprocessing object on a printed matter is deteriorated and therefore a postprocess (cutting with a trim mark, color reproductivity evaluation using a color patch or the like) may be performed in low precision.

SUMMARY

An image forming apparatus according to an aspect of the present disclosure includes a print engine and a control unit. The print engine is configured to eject an ink droplet from a nozzle and thereby print an image to be printed on a print sheet. The control unit is configured to control the print engine. When performing on-sheet preliminary ink ejection, the control unit (a) determines a nozzle that performs the on-sheet preliminary ink ejection, (b) randomly selects on the print sheet an ejection position candidate of an ink droplet ejected from the determined nozzle, (c) determines whether the selected ejection position candidate is included by a mask area that includes a postprocessing object, (d1) if the selected ejection position candidate is not included by the mask area, sets as the selected ejection position candidate an ejection position of an ink droplet ejected from the determined nozzle, and (d2) if the selected ejection position candidate is included by the mask area, does not set as the selected ejection position candidate an ejection position of an ink droplet ejected from the determined nozzle and sets an ejection position of an ink droplet ejected from the determined nozzle outside of the mask area.

These and other objects, features and advantages of the present disclosure will become more apparent upon reading of the following detailed description along with the accompanied drawings.

