Patent ID: 8191986
Filing Date: 2012-06-05
Classification: B41J,G06K

Abstract:
1. An image forming apparatus comprising: a recording head having a plurality of nozzles ejecting ink onto a recording medium, the nozzles constituting nozzle lines arranged in a sub-scanning direction parallel to a feeding direction of the recording medium and in a main-scanning direction orthogonal to the feeding direction, the recording head being configured to scan in a forward scanning direction and in a backward scanning direction along the main scanning direction to form dot images on the recording medium; an imaging unit configured to image the dot images at a predetermined position on the recording medium; a detection unit configured to detect a positional shift amount of the dot images formed in a forward scanning of the recording head, a positional shift amount of the dot images formed in a backward scanning of the recording head, an inclination amount of the recording head in the forward scanning, and an inclination amount of the recording head in the backward scanning based on calibration image data obtained by imaging two first marks and two second marks in a single view by the imaging unit, the two first marks being dot images simultaneously formed on the recording medium while the recording head is moved in the forward scanning direction by using different nozzles arranged in a same nozzle line in the main scanning direction, the center positions of the first marks being detectable, the two second marks being dot images simultaneously formed on the recording medium while the recording head is moved in the backward scanning direction by using the same nozzles having been used to form the first marks and by setting an offset value corresponding to a predetermined distance from the first marks, the center positions of the second marks being detectable; and a correction unit configured to correct a drive of the recording head based on the positional shift amounts and the inclination amounts of the recording head detected by the detection unit.