Image-forming apparatus for use with negatively-charged toner and featuring a negatively-chargeable image-bearing member, and process cartridge using same

Abstract

An image-forming apparatus includes an image-bearing member for holding thereon an electrostatic latent image; a charging device for electrostatically charging a surface of the image-bearing member; an exposure unit for forming the electrostatic latent image on the image-bearing member by exposing to light the image-bearing member having been charged by the charging device; and a developing unit which has at least a toner-carrying member for carrying and transporting a negatively-chargeable toner thereon and developing the electrostatic latent image by a contact developing system to form a toner image. In the triboelectric series relationship between the toner and a surface layer of the image-bearing member, the surface layer of the image-bearing member has a charge polarity which is a different polarity with respect to the charge polarity of the toner in the developing unit. The image-bearing member includes the electrostatic latent image including a surface potential, as a nonimage area potential (Vd) within a range of −500 to −800 V, and as an image area potential (Vl), at which the maximum toner image density is to be obtained, within a range of −50 to −200 V. A process cartridge includes the above-described image-bearing member.