Patent ID: 8837984

Claim:
An image forming system comprising: a first developer container configured to store developer; a second developer container configured to store developer, the second developer container having a capacity larger than the first developer container; and an image forming main unit having a structure configured to allow one developer container selected from a group including the first developer container and the second developer container to be removably installed therein, wherein the first developer container includes a first housing and a first agitating member, the first housing being configured to form a first developer storage chamber in which developer is storable, the first agitating member being rotatable to agitate the developer in the first developer storage chamber, wherein the second developer container includes a second housing and a second agitating member, the second housing being configured to form a second developer storage chamber in which developer is storable, the second agitating member being rotatable to agitate the developer in the second developer storage chamber, the second agitating member having a construction equivalent to that of the first agitating member, wherein the first housing includes a lower portion that defines a lower part of the first developer storage chamber and is disposed below an axis of rotation of the first agitating member, and the second housing includes a lower portion that defines a lower part of the second developer storage chamber and is disposed below an axis of rotation of the second agitating member, the lower portions of the first and second housings being equally positioned relative to the corresponding agitating member and having equally shaped inner surfaces, while the first and second housings further include portions that define parts of the first and second developer storage chambers other than the lower parts defined by the lower portions, and have inner surfaces shaped differently from each other whereby the capacity of the second developer storage chamber is larger than that of the first developer storage chamber, wherein the first housing includes a first frame and a second frame combined together to form the first developer storage chamber, and the second housing includes a third frame and a fourth frame combined together to form the second developer storage chamber, and wherein a portion of the third frame which forms the second developer storage chamber has a capacity larger than a portion of the first frame which forms the first developer storage chamber, and a portion of the fourth frame which forms the second developer storage chamber has a capacity larger than a portion of the second frame which forms the first developer storage chamber.