Patent ID: 7519318

Claim:
An electrophotographic image forming device, comprising: an image holder on which an electrostatic latent image is formed; a magnetic roller forming a magnetic brush including nonmagnetic toner and a magnetic carrier using a magnetic force; a plurality of donor rollers, including a toner layer formed of toner received from the magnetic brush of the magnetic roller on an outer circumference of each of the donor rollers, located opposite to the image holder; a bias applying unit applying a developing bias voltage to develop the toner from the plurality of donor rollers directly onto the electrostatic latent image via a developing gap; and a charger used to form the electrostatic latent image on the image holder; wherein the charger and the bias applying unit control the potential of the developing bias voltage and potentials of an image portion and a non-image portion of the electrostatic latent image so that a toner consumption rate of each of the donor rollers is about 70% or less during image development.