A remaining toner amount detection device includes four electrodes and a controller. Each electrode has an arc shape along an outer circumferential surface of a toner bottle, and the four electrodes are spaced a certain distance apart in a circumferential direction so as to surround the toner bottle. The controller detects a remaining toner amount inside the toner bottle by using the four electrodes. The controller determines whether at least one of a first electrostatic capacity value between one pair of adjacent electrodes and a second electrostatic capacity value between the other pair of adjacent electrodes falls within a threshold range. In response to determination that at least one of the electrostatic capacity values falls within the threshold range, the controller detects a remaining toner amount inside the toner bottle based on an electrostatic capacity value, and outputs the detected remaining toner amount.

An image forming apparatus, includes: plural image forming units each including an image holding member and configured to form an image that is to be transferred to a recording medium on the image holding member using a dry toner, the number of the plural image forming units being at least five; and plural developing devices each of which is provided in each of the plural image forming units and supplied with the dry toner and a dry carrier, each of the plural developing devices including a dry toner adhering unit that has a length equal to or longer than a length of a long side of an A3 size and to which the dry toner adheres, the dry toner adhering unit being configured to cause the dry toner adhering to the dry toner adhering unit to adhere to the image holding member.

An image forming apparatus includes a storage portion, a cover member, a locking mechanism, an unlocking portion, and a contact portion. The storage portion conveys developer stored therein in a conveying direction parallel to a rotation axis by being rotated around the rotation axis parallel to a horizontal plane in a first direction. The cover member opens and closes an insertion hole portion, into which the storage portion is inserted, in a side face of the apparatus body. The locking mechanism imposes a restriction on a state change of the cover member from a closed state to an open state. The unlocking portion removes the restriction on the state change imposed by the locking mechanism as a lever portion swings in a second direction opposite the first direction. The contact portion includes a curved surface and rotates integrally with the storage portion to come into contact with the lever portion.

A developer storage container includes a storage portion, a communication portion, a scooping portion, and a guide portion. The storage portion conveys developer stored therein in a conveying direction along a rotation axis by being rotated around the rotation axis in a specific direction. The communication portion connects the storage portion to an opening portion facing the conveying direction. The scooping portion includes a scooping surface facing the specific direction at an end of the storage portion on a downstream side in the conveying direction and radially outside the communication portion to scoop up the developer in contact with the scooping surface as the storage portion rotates in the specific direction. The guide portion lies radially inside the scooping portion to be contiguous with the scooping surface and an inner peripheral surface of the communication portion, and guides the developer scooped up by the scooping portion to the communication portion.

A developer storage container includes a storage portion, a communication portion, and a gear portion. The storage portion conveys developer stored therein in a conveying direction along a rotation axis by being rotated around the rotation axis in a specific direction. The communication portion is tubular coaxial to the rotation axis and extending in the conveying direction from a downstream end in the conveying direction, and connects the storage portion to an opening portion facing the conveying direction. The gear portion includes a disc-shaped support portion provided for an outer peripheral part of the communication portion concentrically with the rotation axis, a tooth portion along an edge of a support surface, orthogonal to the rotation axis, of the support portion, and a rib extending on the support surface radially from the tooth portion or the outer peripheral part without reaching the other; and receives rotational driving force supplied from outside.

A developer storage container includes a storage portion, a communication portion, and a gear portion. The storage portion conveys developer stored therein in a conveying direction parallel to a rotation axis by being rotated around the rotation axis in a specific direction. The communication portion has a tubular shape coaxial to the rotation axis and extending in the conveying direction from an end of the storage portion on a downstream side in the conveying direction, includes an inner peripheral part that gradually increases its diameter in the conveying direction, and connects the storage portion to an opening portion that has an opening facing the conveying direction. The gear portion is provided for an outer peripheral part of the communication portion and receives a rotational driving force supplied from the outside.

A powder container includes a container body to store powder. The container body includes an inner peripheral surface of a spiral shape and rotates around a longitudinal axis to convey the powder by the spiral shape in one direction. The inner peripheral surface has a substantially polygonal shape having rounded corners or a shape in which sides of the substantially polygonal shape are recessed, in cross section orthogonal to a longitudinal direction of the longitudinal axis at a predetermined position. The inner peripheral surface has a region in which the cross-sectional shape at a position shifted from the predetermined position by a predetermined amount within one pitch of the spiral shape in the longitudinal direction is a shape obtained by rotating the substantially polygonal shape having the rounded corners or the shape in which the sides of the substantially polygonal shape are recessed, around the longitudinal axis.

An engaging portion 30 is provided which is engageable with a portion-to-be-engaged 11b a displaceable integrally with a developer receiving portion 11 with a mounting operation of a developer supply container 1 to displace 11 in an upward direction U to bring a receiving opening into communication with a discharge opening. An engaging portion 30 includes a first engagement surface 31a extending in the upward direction U as going toward a developer accommodating portion of the developer supply container 1, and a second engagement surface 32a provided at a position closer to the developer accommodating portion than the first engagement surface 31a. When the receiving opening in communication with a shutter opening, a height of an end of the first engagement surface 31a close to the developer accommodating portion is higher than the second engagement surface 32a.

A developer supply container 1 is detachably mountable to a developer receiving apparatus including a developer receiving portion 11 provided with a receiving port 11a for receiving a developer, a portion-to-be-engaged 11b a displaceable integrally with the developer receiving portion 11. The developer supply container 1 includes an engaging portion 30 and a discharging portion provided with a shutter opening 4j for discharging the developer accommodated in a developer accommodating portion. The engaging portion 30 is provided at only one side with respect to a predetermined direction crossing with a mounting direction of the developer supply container 1 in the crossing with a displacing direction of the developer receiving portion 11. The engaging portion 30 engages with the portion-to-be-engaged 11b with a mounting operation of the developer supply container 1 to bring the receiving port 11a in the communication with the shutter opening 4j.

An image forming apparatus includes a toner container, a storage part, a cover and an opening/closing mechanism. The toner container includes a shutter. The cover is movable between a closed position for closing the storage part and an opened position for opening the storage part. The opening/closing mechanism closes a supply port by rotating the shutter in accordance with an opening operation for moving the cover to the opened position and opens the supply port by rotating the shutter in accordance with a closing operation for moving the cover to the closed position, in a state where the toner container is attached to the storage part. The toner container includes an interference portion which interferes with the opening/closing mechanism to prevent the toner container from being attached to the storage part in a case where the cover is not moved to the opened position normally.