A rotation detection device includes a light emitting portion, a light-passing control member, and a light receiving portion. The light-passing control member controls passing of the light from the light emitting portion. The light receiving portion outputs a light receiving signal based on the light received by the respective light receiving elements as detection signals representing detection results of the rotation by the rotator. A first virtual extended line that extends the first opening margin and a light-receiving-portion center line along the first direction passing through the respective light receiving elements at the light receiving portion pass through positions shifted from a rotational center of the light-passing control member. The light receiving portion is arranged such that the first virtual extended line corresponds to the light-receiving-portion center line, when the first opening margin passes through an optical path from the light emitting portion to the light receiving portion.

An apparatus includes an image bearing member, a developer container having a replenishment port, a developer bearing member, a detection portion configured to output remainder amount information corresponding to the amount of developer accommodated in the developer container, a notification portion capable of notifying a first state, and a second state, and a control portion, wherein the maximum amount of the developer that the developer container is capable of accommodating is larger than a value obtained by adding the amount of the developer accommodated in a replenishment container containing the developer for replenishment to the first amount, and wherein notification of the second state corresponds to notification of a case where the amount of the developer remaining in the developer container is larger than a case where the amount of the developer remaining in the developer container is the smallest.

Provided is an image forming unit including a photosensitive unit including an image bearing member, a developing unit including a developer bearing member and a container capable of containing a developer, a rotation shaft, the developing unit being rotated around the rotation shaft and positioned at one of a development position where the developer bearing member supplies the developer to the image bearing member and a separation position where the developer bearing member separates from the image bearing member, and a sensing portion sensing a variation or an amount corresponding to an amount of the developer contained in the developing unit. The rotation shaft is located below a developing portion, which is formed of the image bearing member and the developer bearing member, in a gravity direction.

Provided is an image forming unit including a photosensitive unit including an image bearing member, a developing unit including a developer bearing member and a container capable of containing a developer, a rotation shaft, the developing unit being rotated around the rotation shaft and positioned at one of a development position where the developer bearing member supplies the developer to the image bearing member and a separation position where the developer bearing member separates from the image bearing member, and a sensing portion sensing a variation or an amount corresponding to an amount of the developer contained in the developing unit. When the developing unit is at the separation position, the sensing portion restricts the rotation of the developing unit thereby receiving a force from the developing unit.

An image forming apparatus includes an apparatus body, an image bearing member, and a process unit attached to the apparatus body, the process unit including a frame including a storage portion configured to store developer, a developer bearing member configured to supply developer to the image bearing member to develop an electrostatic latent image; and a circuit board attached to the frame, wherein the circuit board includes a light emitting portion configured to emit light, and a light receiving portion configured to receive the light emitted from the light emitting portion and having passed through an interior of the storage portion.

A toner conveying apparatus includes a frame body, a conveyance member, a light transmission portion, a light emission portion, a light reception portion, and a rubbing member. The frame body forms a conveyance passage surrounded by a wall portion and is provided with a reception inlet for receiving toner from outside. The conveyance member is provided in the conveyance passage and rotates around a first rotation axis to convey the toner. The light transmission portion that is provided in the wall portion and has translucency. The light emission portion emits light toward an inside of the conveyance passage through the light transmission portion. The light reception portion receives the light emitted from the light emission portion through the light transmission portion. The rubbing member rubs on the light transmission portion by being rotated around a second rotation axis extending in a direction crossing the first rotation axis.

A toner level detector, includes: a toner cartridge storing toner and having one side provided with a light-permeable region; an agitator, which is rotatably disposed in the toner cartridge and agitates the toner; a reflective region disposed on an inner surface on the other side of the toner cartridge; a first cleaner disposed on one side of the agitator; a second cleaner disposed on the other side of the agitator; and a transceiver, which is disposed on a body outside the toner cartridge, and outputs an emitting signal to the reflective region through the light-permeable region, wherein the reflective region reflects the emitting signal to generate a reflective signal received by the transceiver through the reflective region, wherein the first cleaner, which is rotating, intermittently cleans the light-permeable region, which is fixed; and the second cleaner, which is rotating, intermittently cleans the reflective region, which is fixed.

An image forming apparatus includes a developing device, a first container, a second container, and a toner supplying device. The toner supplying device includes first and second conveyance members that convey the toner in the first and second containers, and first and second sensing shafts that are used to sense the remaining quantities of toner there. The first and second sensing shafts have a first or second light-shielding plate that moves into and out of the optical path of an optical sensor. Of the first and second light-shielding plates, one rotates together with the first or second conveying member selectively driven and makes contact with the other, and thereby makes it move out of the optical path of the optical sensor.

An image forming apparatus, including: a photoconductor; a developing device; a developer storage; a supplier configured to supply developer; an optical sensor; and a controller configured to execute: a developing process of developing an electrostatic latent image on the photoconductor; a usage-amount obtaining process of obtaining a usage amount of the developer; a supplying process of supplying the developer to the developing device every time when the obtained usage amount becomes equal to or greater than a first threshold; and a detecting process of detecting, by the optical sensor, an amount of the developer in the developing device every time when the obtained usage amount becomes equal to or greater than a second threshold larger than the first threshold, and wherein the controller is configured to execute the detecting process in a period different from a period in which the developing process is being executed.

An image forming apparatus includes: a detection unit configured to detect an amount of developer stored in a developing container and to output remaining amount information; and a control unit configured to perform control, during a replenishment of the developer to the developing container using a replenishment container, to cause a display unit to display a message related to the replenishment. When the replenishment is instructed, the control unit is further configured to perform a first control during the replenishment in a case where the remaining amount information indicates a first remaining amount, and configured to perform a second control different from the first control during the replenishment in a case where the remaining amount information indicates a second remaining amount greater than the first remaining amount.