Determining image transfer point at drum in multi-colour image production system

摘要

The image transfer point determination method includes suppressing a speed change e.g. after passing through the fixing unit (16), if the distance between the image transfer points (25) of each colour varies, so that the superimposition of the different colours is correctly carried out. After the determining of a first image transfer point (A), the position of a second image transfer point (B) is determined. So that the distance between the points (A, B) is equal to a whole number multiplication fo a reference length, which corresponds to a speed fluctuation cycle of the drive system. A temporary position or an arrangement range of an i (equal or greater than 3) th image transfer point from the top side of the conveyor line is established. The most shortened conveyor line is determined according to the contact or the separation position, activated by the switching mechanism (30), for each of the first to the (i-1)th image transfer point under the conveyor lines (17) to the temporary position extending from the first to the (i-1)th image transfer position. 3) A position of a point near the temporary position or inside the arrangement range is reached to obtain the shortest line (step 2). So that the shortest conveyor line is equal to a whole number multiplication of the reference length. 4) Position of ith image transfer points is determined based on (i-1) points.