A powder conveying device includes a drop conveyance passage, an intersecting conveyance passage, a conveying screw, and a floating member. Powder entering from an inflow port drops in the drop conveyance passage. The intersecting conveyance passage communicates with a lower end of the drop conveyance passage and extends in an intersecting direction that intersects the drop conveyance passage. The conveying screw is disposed in the intersecting conveyance passage and rotates in a specified direction to convey the powder in the intersecting direction. The floating member is movably installed in the drop conveyance passage and floats in the drop conveyance passage to move by contact with the conveying screw. The inflow port and the floating member interfere with each other to prevent the floating member from coming out of the inflow port of the drop conveyance passage.

A toner case includes a case main body, a transmission member, and a cover. The case main body contains a toner and rotates around a rotation axis line. The transmission member is attached to an outer circumferential face of the case main body and configured to transmit rotation driving force to the case main body. The cover is configured to cover an opening part arranged at the case main body. The case main body includes a rotation restricting part and a movement restricting part. The rotation restricting part is configured to restrict a rotation of the transmission member with respect to the case main body. The movement restricting part is configured to restrict a movement in a direction of the rotation axis line of the transmission member with respect to the case main body. The transmission member is positioned between the cover and the movement restricting part.

An image forming apparatus comprising a developing agent storage section including a discharge port for discharging the developing agent; a developing agent mixer configured inside the developing agent storage section to stir the developing agent and move the developing agent towards the discharge port; a motor which rotates at least the developing agent mixer; a motor control section which rotates the motor at either a first speed at which the developing agent is not discharged from the discharge port or a second speed higher than the first speed to discharge the developing agent from the discharge port; and a device control section which controls the motor control section to switch the rotation speed of the motor to the second speed at a timing different from the timing when the developing roller develops the electrostatic latent image.

A stirring/conveying member has a rotary shaft rotatably supported in a powder container, a first helical blade formed on the circumferential surface of the rotary shaft and conveying powder in the axial direction by the rotation of the rotary shaft, and a second helical blade formed on the circumferential surface of the rotary shaft to overlap the forming region of the first helical blade, spiraling in the opposite phase to the first helical blade, and having a smaller radial height than the first helical blade. The first helical blade crosses the second helical blade at least at one place in one turn about the rotary shaft. At least one of the radial heights of the first and second helical blades equals zero at the intersection of the first and second helical blades.

A developer accommodating unit for accommodating a developer for image formation includes a flexible container provided with an opening 35a for permitting discharge of the developer, a frame for accommodating the flexible container and for accommodating the developer to be discharged from the flexible container, and an urging member 21 for urging a developer accommodating bag toward the frame for accommodating the developer accommodating bag 16. By this, it is possible to satisfactorily effect discharge of the developer from the flexible developer accommodating bag 16.

A toner cartridge includes a casing, a toner conveyance unit, a cover, and a first protrusion. The casing includes a first toner-accommodating section having a first internal space for accommodating toner. The first toner-accommodating section has a first opening. The toner conveyance unit is rotatable and configured to convey toner from the first internal space to the first opening. The cover covers the first opening and has a second opening for allowing toner to be discharged therethrough. The cover has a circumferential surface at which a plurality of gear teeth is provided. The gear teeth are configured to move a developing shutter provided at a developing unit for opening or closing an opening of the developing unit. The first protrusion is configured to release the developing shutter from a locking member of the developing unit for locking the developing shutter.

A developing device includes a developing container and a second stirring member. The developing container includes a second feeding chamber and a developer discharge outlet disposed on the downstream side end of the second feeding chamber. The second stirring member includes a second feeding blade, a restricting part for conveying developer in the opposite direction to the second feeding blade, and a discharging blade for conveying the developer in the same direction as the second feeding blade so as to discharge the developer from the developer discharge outlet. The second rotation shaft includes a large shaft diameter part provided with the second feeding blade, a small shaft diameter part provided with the restricting part and the discharging blade, and a shaft diameter changing part positioned at a boundary between the large shaft diameter part and the small shaft diameter part.

A developer accommodating unit for accommodating a developer for image formation includes a flexible container provided with an opening 35a for permitting discharge of the developer, a frame for accommodating the flexible container and for accommodating the developer to be discharged from the flexible container, and an urging member 21 for urging a developer accommodating bag toward the frame for accommodating the developer accommodating bag 16. By this, it is possible to satisfactorily effect discharge of the developer from the flexible developer accommodating bag 16.

A cartridge includes a shutter that opens and closes when the cartridge is attached and detached to a developing unit or image forming apparatus. The cartridge includes a casing having a chamber with a first opening at one end portion allowing toner to flow out of the casing. The cartridge includes a cover that covers the first opening, movable with the casing and having a second opening allowing toner to flow out of the cover. The shutter is located at the one end portion and has a protrusion further from the one end portion than the cover. The developing unit supports the protrusion when the cartridge is mounted thereon, and the casing pivots with the cover relative to the developing unit between a first position where the shutter closes the second opening and a second position where a third opening of the shutter overlaps the second opening.

A developer accommodating unit for accommodating a developer for image formation includes a flexible container provided with an opening 35a for permitting discharge of the developer, a frame for accommodating the flexible container and for accommodating the developer to be discharged from the flexible container, and an urging member 21 for urging a developer accommodating bag toward the frame for accommodating the developer accommodating bag 16. By this, it is possible to satisfactorily effect discharge of the developer from the flexible developer accommodating bag 16.