A developing device includes a first transport member and a second transport member that are respectively disposed in a first transport path and a second transport path arranged in a vertical direction and that transport developer so as to circulate the developer between the first transport path and the second transport path; a developing member that is disposed to face the first transport path and that receives the developer from the first transport path; and a third transport member that is disposed in a third transport path through which the developer that has not been used by the developing member is collected and transported to the second transport path. A central shaft of the second transport member is disposed farther in a vertically upward direction than is a central shaft of the third transport member.

A developing device includes a first transport member and a second transport member that are respectively disposed in a first transport path and a second transport path arranged in a vertical direction and that transport developer so as to circulate the developer between the first transport path and the second transport path; a developing member that is disposed to face the first transport path and that receives the developer from the first transport path; and a driving device that operates such that a relative speed ratio between a rotational speed of the developing member and a rotational speed of the second transport member is changeable.

Provided is a developing device having a first transport member and a second transport member that are disposed in a first transport path and a second transport path provided at an upper side and a lower side in a gravitational direction. The transport members transport a developer so as to cause the developer to circulate between the first transport path and the second transport path. A partition wall that separates the first transport path and the second transport path from each other and has an opening including an open-close member that opens and closes the opening.

A developing device includes a first transport member and a second transport member that are respectively disposed in a first transport path and a second transport path arranged in a vertical direction and that transport developer so as to circulate the developer between the first transport path and the second transport path; a developing device body in which the first transport path and the second transport path are formed; and a developer discharging structure that discharges excess developer discharged from the first transport path to outside through the second transport path or through a space between an end portion of the second transport path and the developing device body.

A developing device includes: a case in which a hollow transporting path is formed; a transporting member configured to transport a developer in the transporting path; a support portion fixed to an end portion of the case by a fastening member to support the transporting member at an end portion of the transporting path; and a cooling unit fixed by being sandwiched between the support portion and the case.

A developing device includes: a development-region passing body that passes a development region while holding a developer; a first transport path in which the developer to be supplied to the development-region passing body is transported at least in a first transport direction; a second transport path in which the developer to be sent to the first transport path is transported at least in a second transport direction; a first connection portion through which a portion of the first transport path positioned short of a first-transport-direction-downstream end of the first transport path and a portion of the second transport path positioned short of a second transport-direction-upstream end of the second transport path are connected to one another; and a first transport member having a rotating shaft on which a helical first forward-transport blade is provided, the helical first forward-transport blade rotating to forward-transport the developer in the first transport direction in the first transport path. The first transport member has a helical reverse-transport blade that reverse-transports the developer in a reverse direction reverse to the first transport direction, the reverse-transport blade is provided on at least a portion of part of the rotating shaft adjacent to the first connection portion, and a reverse-direction-downstream end of the reverse-transport blade reaches at least a first-transport-direction-upstream end of the first connection portion.

A toner conveying device includes a toner conveying section and a toner conveyor. The toner conveying section includes a bent portion and an outlet port. The bent portion bends in a predetermined direction. The outlet port discharges toner. The toner conveyor is bendable and driven by a driving device to rotate to convey toner. The toner conveyor is disposed in the toner conveying section such that a first end of the toner conveyor is coupled to the driving device and a second end of the toner conveyor is a free end. The toner conveyor includes a reverse-flow conveying portion, between the outlet port and the free end, to convey the toner from the second end to the first end.

A powder container includes a container body, a spiral projection, and a convex portion. The container body stores powder and is rotatable around an axis of the container body. The spiral projection is inside the container body. The convex portion includes a flat surface portion and protrudes inward from an inner wall surface of the container body. A virtual plane including the flat surface portion passes through the axis.

An image forming apparatus includes a toner container, a toner conveyance portion, a container attachment portion, and a biasing mechanism. The toner container has a toner outflow port at a tip portion thereof. The toner conveyance portion is provided in the toner container and conveys toner in the toner container toward the toner outflow port. The container attachment portion supports the toner container. The biasing mechanism applies a biasing force to change the toner container from a horizontal attitude to an inclined attitude in accordance with a toner conveyance operation of the toner conveyance portion. When the toner container is in the inclined attitude, the toner outflow port faces diagonally downward.

A powder container case includes a first member, a second member, a main joint, and an additional joint. The first member and the second member are joined to form an edge portion of a case opening. The main joint is disposed between the first member and the second member, and has an end portion at the edge portion of the case opening. The additional joint is disposed adjacent to the end portion of the main joint.