Patent ID: 6714748
Filing Date: 2004-03-30
Classification: G03G

Abstract:
An image forming apparatus comprising:a plurality of image forming units for forming different color images on recording paper, said plural image forming units including a first color image forming unit for forming a first color image, and at least one second color image forming unit for forming a second color image; and test-pattern image forming control means for controlling said first and second image forming units to form a test-pattern image composed of first and second marks different in density, which are arranged adjacent to one another without any gap therein between, based on test-pattern image data that includes first data serving to arrange a plurality of first color lines, each having a predetermined line width, at a predetermined pitch by said first color image forming unit, second data serving to form said first mark by arranging a plurality of second color lines, each having a line width equal to that of the individual first color line, at a pitch equal to that of said first color lines by said at least one second color image forming unit so as to overlap with said first color lines within a first region occupying part of an area where said plural first color lines are arranged, and third data serving to form said second mark by displacing a plurality of second color lines in a direction perpendicular to said first color lines within a second region contiguous to said first region and by arranging said second color lines, each having a line width equal to that of the individual first color line, at a pitch equal to that of said first color lines by said at least one second color image forming unit; and each of said first and second color lines is a transverse line extending in a primary scanning direction perpendicular to a direction of conveyance of the recording paper; and said test-pattern image composed of said first and second marks contains a longitudinal succession of portions of said plural first color lines extending transversely and is formed on the recording paper at least at scanning-start- and scanning-end-side marginal regions in the secondary scanning direction.