Patent ID: 7650101

Claim:
An image forming apparatus comprising: a developer carrying member configured to carry developer; first and second rotary members arranged parallel to each other and configured to rotate to agitate and convey the developer; and an enclosure having an inside space to contain the developer, the inside space being divided by a partition with communication openings formed therein at opposite ends thereof into a first chamber, said first rotary member being positioned in said first chamber and being configured to maintain the developer above a first level in said first chamber and to supply the developer to the developer carrying member while agitating and conveying the developer, and a second chamber, said second rotary member being positioned in said second chamber and being configured to communicate developer from said second chamber to the first chamber through at least one of the communication openings, and to maintain the developer at a second level in said second chamber lower than the first level, the second rotary member circulating the developer from the first chamber through at least another one of the communication openings wherein said first rotary member has a shaft diameter which is greater than that of said second rotary member and is substantially constant throughout a length portion thereof, an outer diameter of said first rotary member being substantially constant throughout a length portion thereof and being substantially equal to that of said second rotary member, wherein a new developer is supplied to said second chamber.