| 摘要 |
PURPOSE:To form a record desirable in density and free from disturbance of an image and color mixing by successively reducing the amplitude of the AC component of developing bias in accordance with developing cycles while satisfying specified conditions. CONSTITUTION:A photosensitive drum 9 uniformly electrostatically charged with a charger 50 is imagewise exposed to light projected from an He-Ne laser light source through a rotary multiface mirror 51 and a focusing lens 52 to form an electrostatic image. This image is developed with a developing device 11A, the drum 9 is again charged with a charger 50, and the second toner image is formed with a developing device 11B. When likewise, the fourth toner image is formed with a developing device 11D, it is transferred to a recording paper with a transfer device 54, and fixed with a fixing device 57. An image superior in density and freed from disturbance and color mixing can be obtained by satisfying 0.2<=VAC/(df)<=1.6, and successively reducing the amplitude VAC of the AC component of developing bias in each developing stage in accordance with developing cycles, where d(mm.) is the gap between the drum 9 and a developer carrying body, and (f) is frequency. |
