Patent ID: 7466933
Filing Date: 2008-12-16
Classification: G03G

Abstract:
1. An image forming apparatus comprising: an image carrier that is to be formed thereon an electrostatic latent image; an electrifying unit that electrifies a surface of the image carrier to a predetermined polarity; an exposure unit that exposes the surface of the image carrier electrified by the electrifying unit, in accordance with image data to form an electrostatic latent image; a development unit that develops the electrostatic latent image formed by the exposure unit with one of developing agents of a plurality of colors to form a developing agent image on the image carrier; a transport mechanism that transports a transferred member to be in contact with the image carrier, the transferred member being transferred to have the developing agent image formed thereon; and a transfer unit that transfers the developing agent image formed on the image carrier to the transferred member transported by the transport mechanism by applying transfer electric charges having polarity opposite an electrified polarity of the developing agent from a surface of the transferred member opposite a surface thereof opposing the image carrier, wherein the transfer unit forms a multicolor developing agent image on the transferred member by sequentially transferring the developing agent images of respective colors made from a plurality of the developing agents on the transferred member while the transport mechanism sequentially transporting the transferred member, wherein when: an amount of required unit area transfer electric charge, which is an amount of transfer electric charge per unit area required by the transfer unit to transfer to the transferred member the maximum weight of developing agent image formed on the image carrier, is less than an amount of a prevention unit area transfer electric charge which is determined on the basis of an amount of developing agent per unit area on the transferred member that is the maximum weight of transferred developing agent image per unit area immediately before the transferred developing agent image is transferred by the transfer unit, wherein on condition that: the amount of required unit area transfer electric charge is taken as Qmin; the amount of prevention per-unit-area transfer electric charge is taken as Qs; the amount of developing agent per unit area on the transferred member is taken as Md; and a predetermined constant used for expressing a relationship between the amount of prevention per-unit-area transfer electric charge Qs and the amount of developing agent per unit area on the transferred member Md is taken as “a”, a reverse transfer prevention relational expression, which is a relational expression for preventing reverse transfer, is represented by Equation (1) shown below, and the amount of prevention per-unit-area transfer electric charge is represented by Equation (2) shown below, and wherein the image forming apparatus is configured to fulfill the reverse transfer prevention relational expression represented by the Equation (1),