Image forming apparatus using liquid developer

1. An image forming apparatus comprising:

an image carrying member on which a toner image is to be formed;

a developing device including a developing roller for supplying a liquid developer containing a solid content to the image carrying member to form the toner image on the image carrying member, a supply roller for supplying the liquid developer to the developing roller, a nip forming roller, disposed so that a supply nip portion is formed between the supply roller and nip forming roller, the liquid developer being discharged to the supply nip portion;

a liquid developer supplying device including a liquid developer flow path in which the liquid developer flows and supplying the liquid developer to the developing device through a discharge port of the liquid developer flow path, the discharge port facing the supply nip portion;

a storage container storing the liquid developer;

a conveying mechanism capable of feeding the liquid developer from the storage container to the liquid developer flow path and feeding the liquid developer in the liquid developer flow path back to the storage container; and

a controller controlling the conveying mechanism;

wherein at the time of non-developing operation in which a toner image forming operation is not performed by the developing device, the controller controls the conveying mechanism to feed at least a part of the liquid developer present in the liquid developer flow path back to the storage container.

2. An image forming apparatus according to claim 1 , further comprising an operation unit giving to the controller information including maintenance information for notifying a maintenance operation, wherein:

the liquid developer supplying device is detachably attached to the developing device; and

when receiving the maintenance information, the controller controls the conveying mechanism to feed a part of the liquid developer present in the liquid developer flow path back to the storage container, causing the liquid developer present near the discharge port to recede from the discharge port.

3. An image forming apparatus according to claim 1 , further comprising an operation unit giving to the controller information including stop information for notifying that the developing device is to be stopped, wherein:

when receiving the stop information, the controller controls the conveying mechanism to feed substantially the entire amount of the liquid developer present in the liquid developer flow path back to the storage container.

4. An image forming apparatus according to claim 1 , wherein:

the conveying mechanism is a pump capable of pressurizing the liquid developer to feed the liquid developer from the storage container to the liquid developer flow path and sucking the liquid developer to feed the liquid developer from the liquid developer flow path back to the storage container.

5. An image forming apparatus according to claim 4 , wherein:

the liquid developer supplying device includes a common flow path forming member having a single common flow path communicating with the storage container, and a plurality of branch supply pipes each including the discharge port and communicating with the common flow path;

the common flow path and the branch supply pipes form the liquid developer flow path; and

the pump is connected to the common flow path forming member.

6. An image forming apparatus according to claim 1 , wherein:

the developing device includes a developer carrying member for supplying the liquid developer to the image carrying member;

the liquid developer supplying device includes a common flow path forming member having a single common flow path communicating with the storage container, and a plurality of branch supply pipes each including the discharge port and communicating with the common flow path;

the common flow path and the branch supply pipes form the liquid developer flow path; and

the discharge ports of the plurality of branch supply pipes are located at predetermined intervals in a rotation axis direction of the developer carrying member.

7. An image forming apparatus according to claim 1 , wherein:

the storage container includes an agitating member agitating the stored liquid developer; and

at the time of a developing operation to form a toner image by the developing device, the controller is so constructed as to be able to control the conveying mechanism to feed the liquid developer from the storage container to the liquid developer flow path and control the agitating member to agitate the liquid developer in the storage container before the toner image forming operation is performed.

8. An image forming apparatus according to claim 1 , wherein:

the liquid developer supplying device includes a supply pipe in which the liquid developer flows, and a plate portion supporting the supply pipe;

the supply pipe includes one end having the discharge port and the other end communicating with the storage container; and

the plate portion holds the one end on a horizontal plane.

9. An image forming apparatus according to claim 1 , wherein:

the liquid developer supplying device includes a common flow path forming member having a single common flow path communicating with the storage container, and a plurality of branch supply pipes each including the discharge port and communicating with the common flow path;

the common flow path and the branch supply pipes form the liquid developer flow path; and

the common flow path extends substantially in a horizontal direction.

10. An image forming apparatus according to claim 1 , wherein:

the controller feeds at least a part of the liquid developer back to prevent the liquid developer from forming a meniscus at the discharge port.