| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for detecting positional deviation hardly influenced by the speed fluctuation of a transfer belt in an image forming device where an image is synthesized by superposing a plurality of images on a single transfer body such as a color copying machine. SOLUTION: Resist patterns RB1 , RB2 , RC1 and RC2 for detecting positional deviation are formed in two lines at the side edge part of the transfer belt 1 of the full color copying machine. The resist patterns are constituted of RB1 , RC1 and RC2 , RB2 where two colors, black B and cyan C, are obliquely opposed. Assuming that time when the resist patterns are read by sensors 1 and 2 is t1a, t1b, t2a and t2b and ta=t1a-t2a and tb=t1b-t2b, the positional deviation between two colors in a main scanning direction is proportional to ta+tb and that between two colors in a subscanning direction is proportional to tb-ta. Then, positional deviation in writing is corrected based on the positional deviation calculated in such a way. |
