Abstract: An image forming apparatus includes a developer that develops a latent image to form an image, a separation unit that separates image information of a job image by color upon writing a latent image of the job image, a comparison unit that compares the image information by color separated by the separation unit with a threshold value previously set with respect to an image concentration, and a driving condition determination unit that determines a driving condition of the developer using a result of comparison by the comparison unit.

Abstract: An image forming apparatus includes a toner forced discharge treatment for executing a toner discharge mode in which toner inside a developing device is forcedly consumed, and a toner discharge judgment treatment capable of judging necessity of execution of the toner discharge mode based on a decision as to whether or not a toner state inside the developing device is in a state of leading to an image quality defect. Further, the apparatus includes a toner forced supply treatment for executing a toner supply mode in which new toner is supplied from a toner replenishment device to the developing device in addition to execution of the toner discharge mode.

Abstract: An image forming apparatus includes a developer that develops a latent image to form an image, a separation unit that separates image information of a job image by color upon writing a latent image of the job image, a comparison unit that compares the image information by color separated by the separation unit with a threshold value previously set with respect to an image concentration, and a driving condition determination unit that determines a driving condition of the developer using a result of comparison by the comparison unit.

Abstract: An electrophotographic developer is provided for realizing high-quality images and superior reproducibility of laser dots in a low coverage region and reduced unevenness of color in halftone solid images. The electrophotographic developer includes a toner and a carrier. The toner has a shape factor of 140 or less and a volume average particle size distribution GSDv of 1.3 or less. The carrier has a coat resin layer on a core material, the coat resin layer containing a conductive powder. The core material has a dynamic electric resistivity of 1 ?·cm or less under an electric field of 104 V/cm in a form of a magnetic brush. The conductive powder has an electric resistivity of 101 ?·cm or greater and 106 ?·cm or less. The carrier has an electric resistivity in a range between 10 and 1×108 ?·cm. An image forming method is also provided wherein the electrophotographic developer is used for development in a developing stage.

Abstract: An image forming apparatus includes a toner forced discharge treatment for executing a toner discharge mode in which toner inside a developing device is forcedly consumed, and a toner discharge judgment treatment capable of judging necessity of execution of the toner discharge mode based on a decision as to whether or not a toner state inside the developing device is in a state of leading to an image quality defect. Further, the apparatus includes a toner forced supply treatment for executing a toner supply mode in which new toner is supplied from a toner replenishment device to the developing device in addition to execution of the toner discharge mode.

Abstract: An electrophotographic developer is provided for realizing high-quality images and superior reproducibility of laser dots in a low coverage region and reduced unevenness of color in halftone solid images. The electrophotographic developer includes a toner and a carrier. The toner has a shape factor of 140 or less and a volume average particle size distribution GSDv of 1.3 or less. The carrier has a coat resin layer on a core material, the coat resin layer containing a conductive powder. The core material has a dynamic electric resistivity of 1 &OHgr;·cm or less under an electric field of 104 V/cm in a form of a magnetic brush. The conductive powder has an electric resistivity of 101 &OHgr;·cm or greater and 106 &OHgr;·cm or less. The carrier has an electric resistivity in a range between 10 and 1×108 &OHgr;·cm. An image forming method is also provided wherein the electrophotographic developer is used for development in a developing stage.