Patent ID: 8107829

Claim:
An image forming apparatus comprising: a plurality of photosensitive members; at least one retaining member positioned in contact with a corresponding photosensitive member and configured to temporarily retain remaining developer remaining on this photosensitive member; a belt arranged opposite to the plurality of photosensitive members; a cleaning device positioned in contact with the belt and configured to collect developer on the belt; a remaining developer collecting unit configured to cause the remaining developer retained by the retaining member to be transferred onto the belt via the photosensitive member and thereafter to be collected by the cleaning device; a plurality of developing units each including a developing roller positioned in contact with a corresponding photosensitive member to supply developer to the photosensitive member, and a development chamber accommodating the developing roller; a plurality of developer receptacles configured to be attached to and removed from corresponding developing units, and each having a developer storage chamber for storing developer; a circulation mechanism configured to circulate developer between the development chamber and the developer storage chamber; a detector detecting the amount of developer stored in the developer storage chamber; a determination unit configured to determine if the amount of developer stored in the developer storage chamber is less than a predetermined amount based on a signal from the detector; and a notifying unit configured to notify a user to replace a developer receptacle when the determination unit determines that the amount of developer stored in the developer storage chamber is less than the predetermined amount, wherein the predetermined amount is set equal to or greater than a remaining amount of developer remaining in the development chamber.