Patent ID: 8081910
Filing Date: 2011-12-20
Classification: G03G

Abstract:
1. An image forming apparatus comprising: a latent image carrier that circulates in a predetermined rotating direction; a charging unit that charges a surface of the latent image carrier with a voltage having the same polarity as a regular charging polarity of a toner having no contact with the surface of the latent image carrier at a predetermined charging position; a latent image forming unit that forms an electrostatic latent image on the surface of the latent image carrier by allowing the voltages of the charged surface of the latent image carrier to be different from each other between an image portion to which the toner is adhered and a non-image portion to which the toner is not adhered at a latent image forming position downstream of the charging position in the rotating direction; a developing unit that has a toner carrier without contact facing the latent image carrier at a developing position downstream of the latent image forming position in the rotating direction and develops the electrostatic latent image as a toner image by transporting a charged toner carried on a surface of the toner carrier to the developing position and applying an alternating voltage as a developing bias; a transferring unit that transfers the toner image on the transfer medium by abutting a transfer medium on the latent image carrier and applying a transferring bias having a polarity opposite to the regular charging polarity to the transfer medium at a transferring position downstream of the developing position in the rotating direction; and a cleaning unit that removes a toner that is charged with a regular charging polarity and remains to be adhered to the surface of the latent image carrier by abutting an abutting member applied with a voltage having a polarity opposite to the regular charging polarity on the latent image carrier at a cleaning position downstream of the transferring position in the rotating direction, wherein the surface of the toner carrier has conductivity and includes a toner carrying area, in which a toner is carried, and a non-carrying area, in which a toner is not carried and through which the conductive surface is exposed, in the developing position, wherein a voltage of the transferring bias is a DC voltage that does not cause discharge between an image portion of the latent image carrier and the transfer medium and that causes discharge between a non-image portion of the latent image carrier and the transfer medium, and in a case where, in the developing position, a voltage of the non-image portion of the latent image carrier is Vo, a voltage of the developing bias at the time when a force generated to bias the toner charged with the regular charging polarity in a direction from the latent image carrier to the toner carrier is maximum is Vmax, and a voltage of the developing bias at the time when a force generated to bias the toner charged with the regular charging polarity in a direction from the toner carrier to the latent image carrier is maximum is Vmin, an equation below is satisfied: