| 摘要 |
PURPOSE:To provide an image forming device which provides stable color balance and image density. CONSTITUTION:In this printer, the amount of charges applied to a photosensitive drum 10, that is, a surface potential SP and development bias voltages VBD applied to developing devices 14, 16, 18 and 20 are independently varied. In order to vary the surface potential SP and bias voltages VBD, the variation amount in contrast potential VC and background potential VBG which are also varied with them are measured through a surface potential sensor 30. In order to estimate the variation in contrast potential VC and background potential VBG more accurately, the sticking amount Q of toner supplied to the photosensitive drum is estimated via a sensor 32 for detecting the sticking amount of toner. According to the results of these estimations, an output from the main electrifier 12 and the development bias voltages VBD applied to the developing devices 14, 16, 18 and 20 are most suitably controlled via the main controller. |
