Patent ID: 7313351

Claim:
A one-component development type developing apparatus comprising a rotatable electrostatic latent image holding member on the surface of which an electrostatic latent image is formed, and using a toner for rendering the electrostatic latent image visible, wherein when the shape factor SF-1 of a toner fine particle is expressed by: SF- 1=( M 2 /A )×(π/4)×100 where A is the projected area of the fine particle and M is the absolute maximum length of the fine particle, then the shape factor SF-1 of the toner is at least 100 and at most 140, wherein the developing apparatus comprises: a toner holding member that is formed from a silicone rubber elastic material and that is for holding the toner and transporting it to the electrostatic latent image holding member; a toner layer regulating member for forming the toner on the toner holding member into a thin layer; and a toner supply member that is formed from a silicone rubber foam and that rotates, in a position opposed to the toner holding member, in a direction opposite to that of the toner holding member, and wherein an AC electric field is formed between the toner holding member and the toner supply member.