| 摘要 |
PROBLEM TO BE SOLVED: To execute an excellent image forming action coping with the lowering of image density and the change of gradient, by making the image forming conditions of a first toner image forming means and a second toner image forming means different from each other. SOLUTION: The process conditions of the first toner image forming means 26A and the second toner image forming means 26B are made different from each other. The process conditions are conditions of electrification, exposure and developing. Put it more concretely, they are the electrifying potential of a photoreceptor drum 21, exposure, developing bias, the rotational speed of a developing sleeve and the like. Then, a first and a second process units 20A and 20B are constituted as the identical process unit so as to reduce the cost. Besides, the process conditions which can be easily changed are made different from each other so that the optimum image forming action can be executed on both of a front surface and a back surface. Since the attachment quantity of toner is reduced specially when the image forming action is executed on the back surface, the process conditions are made different so that the quantity of the toner attached to the photoreceptor drum 21B becomes more than the quantity of the toner attached to the photoreceptor drum 21A. |
