| 摘要 |
<P>PROBLEM TO BE SOLVED: To stably form a toner image with good image quality by forming a patch image with little unevenness in density and making density control factors most appropriate based on the density. <P>SOLUTION: The following actions are taken as preliminary actions before a patch image formation. In a preliminary action 1, spike noise is eliminated and a background profile is obtained by sampling sensor output for one round of an intermediate transfer belt (steps S23, S24) after carrying out correction of a density sensor and setting of reference light quantity (steps S23, S24). In a second preliminary action 2, installment is carried out to developing positions in order from a yellow (Y) developing device and rotating drive of a developing roll is carried out (steps S26, S27) while setting developing bias to the minimum. Thus, by carrying out the rotary drive of the developing roll regarding all colors while switching the developing devices (steps S28, S29), appearance of density unevenness in the patch image is prevented. <P>COPYRIGHT: (C)2004,JPO |
