| 摘要 |
PROBLEM TO BE SOLVED: To shorten time from starting copying till finishing it or to reduce copying cost. SOLUTION: A joint detecting sensor 340 detects the joint of an endless belt. By controlling a retreat clutch 405, a retreat mechanism control part 404 switches a retreat mechanism to a basic position and a retreat position. The basic position is a position for supplying paper to all of cyan, magenta, yellow and black image forming units, and the retreat position is a position for supplying the paper only to the black image forming unit. The retreat mechanism control part switches the retreat mechanism from the basic position to the retreat position only when specified time elapses after the sensor 340 detects the joint of the endless belt and when a monochrome image forming mode is set. |
