A color image forming apparatus includes a photoreceptor medium, an exposing
unit,
a plurality of developer units, and a power supply. The exposing unit scans light
onto the photoreceptor drum to form a latent electrostatic image. The plurality
of developer units include developer rollers supplying toner to the latent electrostatic
image to develop the latent electrostatic image into a toner image. Each developer
unit contains toner of a different color, and the developer units are arranged
around the photoreceptor medium so that the developer rollers are separated by
a development gap from the photoreceptor medium. The power supply selectively applies
a first bias allowing toner to be supplied through the development gap to the photoreceptor
medium on which the latent electrostatic image is formed and a second bias preventing
toner from passing through the development gap.
