Patent ID: 8186794

Claim:
A method of correcting an alignment error of an array inkjet heading having a plurality of head chips to print a main scanning line, the method comprising: determining a reference head chip; printing a plurality of reference lines in the main scanning direction to be separated from one another at a reference interval in a sub-scanning direction using the reference head chip, and printing a plurality of test lines which are offset by a multiple m, where m is an integer, of a test interval with respect to the reference interval using other head chips; and determining one of the plurality of test lines that matches any of the plurality of reference lines with respect to each of the head chips, and determining an amount of offset of the determined test line of each head chip as an amount of offset of each head chip; wherein the determining of the amount of offset of each head chip comprises: determining an amount of offset of a matching test line of a plurality of test lines of a preceding head chip closer to the reference head chip than a corresponding head chip and a plurality of test lines of a corresponding head chip as relative offset amount of the corresponding head chip with respect to the preceding head chip; and determining a sum of the offset amount of the preceding head chip with respect to the reference head chip and the relative offset amount of the corresponding head chip with respect to the preceding head chip as an amount of the offset of the corresponding head chip with respect to the reference head chip.