Patent ID: 7502578

Claim:
A developing apparatus having one or more developing units, said developing unit comprising: a developer containing chamber for containing a single component developer; a developer supply chamber which is supplied with said single component developer in said developer containing chamber; developing means which is disposed in said developer supply chamber and develops an electrostatic latent image on one or more image retaining members by said single component developer; a boundary wall, disposed between said developer containing chamber and said developer supply chamber, which has a first and a second opening; and an opening and closing member for opening and closing said first opening; wherein said single component developer is supplied, through said second opening, from said developer containing chamber into said developer supply chamber; and said opening and closing member opens and closes, in response to a quantity of said single component developer supplied into said developer supply chamber and allows said single component developer to move in only one direction from said developer supply chamber to said developer containing chamber; wherein said developing means comprises a developing roller for developing said electrostatic latent image; and a supply roller for supplying said developing roller with said single component developer; wherein said first opening is formed, relative to said second opening, at a downstream side along a rotational direction of said supply roller; wherein said second opening is formed under a center of a rotation axis of said supply roller; and said first opening is formed over an uppermost point of an outer surface of said supply roller; and which further comprises a stirring member disposed in said developer containing chamber, wherein a center of a rotation axis of said stirring member is positioned over said second opening.