A high image quality electrophotographic image forming apparatus is
provided without increasing the size and cost, and reducing the life
thereof. The potential difference (contrast potential) between a
photoreceptor and a development roller for supplying toner to the
photoreceptor by the use of a carrier is set to be smaller in the
non-image area irrelevant to the printing operation, and set to be larger
in the image area relevant to the printing operation. In this manner, the
damage to the photoreceptor caused by the adhesion of the carrier is
reduced in the non-image area irrelevant to the printing operation, and
the fog is reduced in the image area relevant to the printing operation.
