| 摘要 |
PROBLEM TO BE SOLVED: To prevent soiling on the back of a transfer material by controlling the timing for supplying a transfer material to a transfer material carrier so as not to lap with an toner image for detection. SOLUTION: In a transportation belt with a perimeter of 760 mm under series print, area inter-paper areas B and D of about 83 mm between paper are generated before and behind two areas A and C which carry a A4 size transfer material, and the density patches are formed in the inter-paper areas. Abutting and spacing of an adsorption roller are synchronized with transfer material transportation by control of a CPU. An adsorption bias =+1.5 kV in the adsorption and an antisticking bias =-1.5 kV when the adsorption part passes the density patch are switched and applied by the CPU. Subsequently, a transfer bias =+1 kV is applied to transfer the image of the first color, a cleaning bias =-1.5 kV is switched and applied to areas between paper, and then electric field cleaning of the density patch is performed. A transfer bias =+1.25, +1.5, +1.75 kV, and the cleaning bias =-1.5 kV are switched and applied to the second, third and fourth color. |
