Ink jet recorder

An ink jet recorder configured to perform an overcoating process, wherein an overcoating ink is discharged onto a sheet of paper on which a registration mark that serves as a reference for identifying an image formation position is printed and on which an image has already been formed, such that the overcoating ink is superimposed on the image, the ink jet recorder comprising:

• a conveying mechanism that conveys the sheet of paper on which the image has already been formed;
• a recording head that functions to discharge the overcoating ink onto a printing surface of the sheet of paper, on which the image has already been formed;
• a reader that is arranged upstream, in a paper-conveying direction, of the recording head and that reads the registration mark printed on the sheet of paper that is conveyed;
• a memory unit that stores data that is set in advance, based on a design correspondence relationship between a printing position of the registration mark and the image formation position in the sheet of paper, wherein the data is discharge data for identifying a discharge pattern of the overcoating ink discharged from the recording head;
• a controller that performs the discharge control of the recording head based on the discharge data;
• and
• a correction unit that corrects the discharge data based on information read for the registration mark,
• wherein, on the sheet of paper on which the image has already been formed, a first registration mark pair and a second registration mark pair are printed, the first registration mark pair and second registration mark pair each consisting of a pair of registration marks that are arranged to be spaced apart in a paper-width direction perpendicular to the paper-conveying direction, the second registration mark pair located posterior to the first registration mark pair in the paper-conveying direction, and
• wherein, based on the actual positional relationship between the first registration mark pair and the second registration mark pair that are read by the reading unit, the correction unit corrects discharge data that corresponds to an image formation area located between the first registration mark pair and the second registration mark pair.