Patent ID: 6937830

Claim:
An image forming apparatus for uniformly charging a photoconductive element in rotation with a charger, exposing imagewise said photoconductive drum charged by said charger to thereby form a latent image, developing said latent image with a developing device using a forward developing system and including a casing, which is formed with an opening facing said photoconductive element, and a developer carrier facing said photoconductive element via said opening, and transferring a developed image to an image transfer member being conveyed, said image forming apparatus comprising: feeding means for feeding a controlled gas to a position upstream, in a direction of rotation of the photoconductive element, of a developing position where the developing device operates; developing zone switching means for selectively causing a developer layer deposited on the developer carrier to contact a developing zone of the photoconductive element in an image formation condition or to part from said developing zone in a stand-by condition; and sealing means for maintaining, in the image forming condition, a gap between the photoconductive element and the casing at a position downstream of the developing zone in the direction of rotation of said photoconductive element or sealing said gap in the stand-by condition.