| 摘要 |
PURPOSE:To always maintain the excellent efficiency of transfer without being affected by the environmental condition of a device or the characteristic of a transfer material and to obtain a transfer image with high image quality by controlling the high-voltage power source of a transfer means so that the quantity of electric charge given to the transfer material from the transfer means becomes a prescribed reference value. CONSTITUTION:A current I1 is measured by preliminarily rotating a photosensitive drum 1 and an intermediate transfer belt 5 when a print switch is turned on. At the preliminary rotating time, a prescribed voltage is impressed on a secondary transfer charger 25. Then, the current I1 flowing to an electrode roller 10 through the belt 5 is measured and stored in a control part 31. Besides, information on the width (w) of a transfer paper S from a size detection sensor for a transfer paper disposed in a paper supply part is stored in the control part 31. When the preliminary rotation is finished and an actual copying action is started, the prescribed voltage is impressed on the charger 25 at a secondary transfer time, first and the current I2 flowing to the roller 10 through the transfer paper and the belt 5 is measured. Besides, the current (i3) per unit length flowing to the transfer paper is calculated. Then, the voltage outputted by the high-voltage power source 30 is adjusted so as to make the current (i3) almost equal to the reference value (i0), which is previously decided, in real time. |
