Patent ID: 7054565

Claim:
An electrophotographic image forming apparatus comprising: a photosensitive medium; a charging unit to charge a surface of the photosensitive medium to a uniform potential; an exposure unit to scan light over the surface of the photosensitive medium to form an electrostatic latent image on the surface of the photosensitive medium; a developing roller to develop the electrostatic latent image by applying a developer to the electrostatic latent image; a developer supplying roller to supply the developer to the developing roller; a transfer unit to transfer the developed image on the surface of the photosensitive medium to a sheet of print paper; a current measuring unit to measure a developing current flowing between the developing roller and the photosensitive medium; and a controlling unit to calculate a value representing at least one of a thickness of a photosensitive film of the photosensitive medium, a thickness of the developer on a surface of the developing roller, and a quantity of development on the surface of the photosensitive medium using the measured developing current, and to display information concerning replacement of a consumable or to control development parameters according to the calculated value.