Developing device including device for selecting varying the thickness of the developing agent

摘要

A developing roller is opposed to a photosensitive drum on which a latent image is carried, and developer supplied to the latent image is held and fed by the developing roller. Developer is supplied from a feeding roller to the developing roller. A thickness defining blade is pressed against the feeding roller to press the feeding roller against the developing roller and form a developer layer of certain thickness on the feeding roller. A developing device thus arranged enables developer to be electrically charged without adding any stress to the developer, and a developer layer of certain thickness to be formed.