Developing device for developing a latent image

Abstract

A developing device includes a charger configured to charge a surface of an image carrier uniformly during its movement, an exposure unit configured to expose an optical image to form an electrostatic latent image on the charged image carrier, a developing unit provided facing the image carrier to supply developing agent to the image carrier to develop the electrostatic latent image. The developing unit includes a first developing roller and a second developing roller arranged at the down stream side of the first developing roller in the moving direction of the image carrier. Further, the developing device includes a bias voltage transformer configured to apply a bias voltage to the first and second developing rollers, a controller configured to control the bias voltage transformer to apply a regular bias voltage of the same polarity as the charged image carrier to the first developing roller when the leading edge of the charged area on the image carrier passes the position facing the first developing roller after the charging to the image carrier has started, and a driver to configured to start to drive the developing unit before the leading edge of the electrostatic latent image formed on the image carrier passes the position facing the first developing roller after the controller controls the bias voltage transformer to apply the regular bias voltage.