Abstract: A system and method for determining, during a pre-rotation period, a proper transfer bias for colors, e.g. YMCK. These proper transfer bias voltages are applied to a primary transfer roller, which enables proper transfer of color images from a photoconductive drum. Four exposure bias voltages for each of YMCK are determined. The first exposure bias voltage for Y is applied to the photoconductive drum, while three predetermined voltages are applied to a primary transfer roller in order to obtain corresponding currents and a voltage/current relationship thereof, from which a proper transfer bias voltage for Y is determined. For all subsequent colors, a proper transfer bias voltage for each subsequent color is determined by employing the Y exposure bias voltage and the exposure bias voltage for each the subsequent colors, MCK. In an exemplary embodiment, it is noted that the proper transfer voltages are obtained during pre-rotation in which the primary transfer roller rotates no more than three times.

Abstract: An image forming apparatus includes an image bearing member, an image forming portion for forming an image on the image bearing member, a contact transferring member for transferring the image formed on the image bearing member onto a transferring medium, a transferring current applying portion for applying a current to the contact transferring member, and a controller for controlling an amount of the current applied by the transferring current applying portion. Images formed on the image bearing member are transferred in a superposed manner onto the transferring medium, which is being conveyed.

Abstract: An image forming apparatus has a latent image forming portion for forming an electrostatic latent image on an image bearing member; a plurality of developing portions for developing the electrostatic latent image on the image bearing member with a developer; a primary transferring portion for transferring by sequentially superposing each developer image developed by the plurality of developing portions on an intermediate transferring member; a secondary transferring portion for collectively transferring onto a transferring material the developer images transferred by being superposed on the intermediate transferring member; and a charging portion for charging the developer images on the image bearing member; wherein the charging portion decides a charging condition in accordance with the order of transferring the developer images onto the intermediate transferring member.

Abstract: An image forming apparatus includes an image bearing member, an image forming portion for forming an image on the image bearing member, a contact transferring member for transferring the image formed on the image bearing member onto a transferring medium, a transferring current applying portion for applying a current to the contact transferring member and a controller for controlling an amount of the current applied by said transferring current applying portion. Images formed on the image bearing member are transferred in a superposed manner onto said transferring medium that is being conveyed.