Patent ID: 6198896
Filing Date: 2001-03-06
Classification: H04N

Abstract:
An apparatus for forming images on record paper, comprising:a moving member with record paper adhered thereon, conveyed at a certain speed;a plurality of image carrying units arranged in a record paper conveyance direction, for forming latent images in conformity with image data through optical scanning on a photosensitive drum, developing the latent images with different developing vessels and transferring the latent images onto record paper lying on said moving member;a correction mark formation unit for forming and transferring mixed color mark trains onto said moving member by means of said plurality of image carrying units, said mixed color mark trains serving as marks for correcting image offsets between color images, said mixed color mark trains each consisting of a plurality of marks which are superposed on each other in an offset manner;a correction value calculation unit for detecting a lightness pattern of said mixed color mark trains transferred onto said moving member, to calculate correction values for image offsets between color images from the phase of said lightness pattern; anda correction unit for automatically correcting offsets between color images on the basis of said correction values;wherein said correction mark formation unit forms, as said mixed color mark trains, a mixed color slanted line mark train consisting of a plurality of transverse line marks substantially orthogonal to the direction in which said moving member moves, and a mixed color slanted line mark train consisting of a plurality of slanted line marks which traverse substantially diagonally the direction in which said moving member moves.