Toner supply roller and developing apparatus

A developing apparatus for forming a toner image by supplying a toner to an electrostatic latent image on a photosensitive body, the developing apparatus comprising:

• a toner cartridge housing a toner as a developer;
• a toner supply roller including a foamed elastic body having a compression spring constant ranging from 0.25 to 5.0 N/mm;
• and
• a developing roller configured to make contact with the toner supply roller and deform due to the deformation of the toner supply roller;
• wherein the toner supply roller has a cutting amount caused by the developing roller in a range of 0.5 to 2 mm, and a pressing force against the developing roller at most 6.0N.

A developing apparatus for forming a toner image by supplying a toner to an electrostatic latent image on a photosensitive body, comprising:

• a toner cartridge housing a toner as a developer;
• an electroconductive toner supply roller positioned to supply the toner;
• and
• an electroconductive developing roller positioned to develop an electrostatic latent image on the photosensitive body with the toner and having an electric resistance in a range between 1×106.5 and 1×1011 (Ω);
• wherein:
• the toner supply roller has an electric resistance which is lower than an electric resistance of the developing roller at an impressed voltage in a range of 100V to 500V;
• and
• a difference between the electric resistance of the toner supply roller and the electric resistance of the developing roller is at least 0.5 expressed in terms of common logarithmic value thereof (Ω).