COLOR IMAGE FORMING APPARATUS, TANDEM DRUM TYPE COLOR IMAGE FORMING APPARATUS AND PROCESS CARTRIDGE USED FOR THE COLOR IMAGE FORMING APPARATUS

摘要

PROBLEM TO BE SOLVED: To provide a color image forming apparatus capable of obtaining high quality image at high printing speed and to provide a process cartridge used for the color image forming apparatus.;SOLUTION: A reflection type photo-sensor 41 detects a mark pattern formed on a transfer belt 33 by a mark pattern formation part 11. Based upon the detection by the sensor 41, a distance difference measurement part 12 measures a distance difference that is a distance by which the mark pattern is displaced from a reference value. A speed detection part 13 detects a moving velocity v1 of the transfer belt 33 during a period from the formation of the mark pattern to the completion of the detection and a moving velocity v2 of it during normal image formation. A speed difference calculation part 14 calculates Δv=v1-v2. In accordance with the distance difference and Δv, a control part 15 controls the timing of image formation so as to reduce color shift.;COPYRIGHT: (C)2004,JPO