An optical sensor has a light emission section and a light reception section so arranged as to sandwich an opening part of a toner container from both sides when the toner container is attached, and a shutter slides in conjunction with the attachment and detachment of the toner container and has a top surface member opening and closing a toner exhaust port of a cleaning device and a side surface member transmitting and blocking light of the optical sensor. A slit orthogonal to a sliding direction of the shutter is formed at the side surface member of the shutter, and the control section performs detection of attachment and detachment of the toner container based on a waveform pattern of light transmitted through the slits which pattern appears in a signal of the optical sensor.

An image forming apparatus includes a developing device, a container, a toner replenishment device, a toner conveyance detection portion, and a control portion. The toner replenishment device includes a plurality of toner replenishment paths through which toner in the container is conveyed and replenished to the developing device. The toner conveyance detection portion detects a toner conveyance error in toner conveyance performed by using the plurality of toner replenishment paths. In a case where the toner conveyance detection portion has detected a toner conveyance error in one of the toner replenishment paths that is in use, the control portion switches to another one of the toner replenishment paths to convey the toner.

An image forming apparatus includes an image bearing member, a charging member, a development member, a developer accommodating portion, a first acquiring portion which acquires developer amount information related to an amount of the developer accommodated in the developer accommodating portion, a second acquiring portion which acquires development drive information related to a movement distance of a surface of the development member, and a control portion which is capable of executing a first mode and a second mode, whose frequency of driving the development member lower than that of the first mode, as an image forming mode. The control portion proposes or determines a change from the first mode to the second mode of the image forming mode on the basis of the developer amount information and the development drive information.

An image forming apparatus includes a mounting portion, an accommodating portion, a remaining toner amount detecting portion, a display portion, and a controller. In a supplying operation, the controller sets a threshold on the basis of a first output value before toner supply from the toner container to the accommodating portion. The controller discriminates whether or not toner in a certain amount or more is supplied to the accommodating portion by comparing the threshold with a second output value after the toner is supplied from the toner container to the accommodating portion. The threshold is a value between the first output value and a third output value when the toner in a total amount accommodated in the toner container that has never been used is supplied to the accommodating portion before supply of the toner, and is closer to the third value than to the first value.

An image forming apparatus includes an apparatus body, an image bearing member, and a process unit attached to the apparatus body. The process unit includes 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. 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.

An image forming apparatus includes an image forming portion including a developer storage portion, a fixing apparatus, a detection portion configured to output a detection signal in accordance with a developer amount in the developer storage portion, and a control portion configured to control a target temperature of the fixing apparatus. The control portion is configured to set the target temperature at a first temperature if the developer amount is a first amount, set the target temperature at a second temperature lower than the first temperature if the developer amount is a second amount smaller than the first amount, and set the target temperature at a third temperature higher than the second temperature if the developer storage portion is supplied with the developer such that the developer amount is increased from the second amount to the first amount.