Abstract: An image forming apparatus includes an image bearing member, a developing unit to develop an electrostatic latent image formed on the image bearing member with toner, and a detachable toner container in which toner for supplying to the developing unit is contained. A measuring unit measures information relating to an amount of toner in the developing unit, and a determination unit determines an amount of toner in the developing unit based on the measured information.

Abstract: An image forming apparatus includes an image bearing member; a developing device; a transfer member; a contact member provided downstream of the transfer member and upstream of the developing device with respect to a movement direction of a surface of the image bearing member and contacting the image bearing member at a contact portion, wherein the surface of the image bearing member passed through a transfer portion reaches the contact portion without being cleaned, a detecting portion for detecting a size of the sheet; and a controller for executing an operation in a cleaning mode for cleaning the contact member. The controller executes the operation in the cleaning mode when the controller discriminates that the size of the sheet detected by the detecting portion is smaller than a size of the toner image.

Abstract: The image forming apparatus includes an image bearing member, a developing unit for developing an electrostatic latent image formed on the image bearing member with toner, a cartridge that is detachably provided in an apparatus main body and that has at least the developing unit, a toner container that is detachably provided in the apparatus main body and that stores toner for supplying to the developing unit, a memory unit that stores information relating to a usage state of the cartridge, a measuring unit that measures an amount of toner in the developing unit, and a determination unit that determines the amount of toner in the developing unit based on information stored in the memory unit, information obtained by measurement by the measuring unit, and a measurement error of the measuring unit, at a time of an initial operation before performing an image forming operation.

Abstract: An image forming apparatus includes an image bearing member; a developing device; a transfer member; a contact member provided downstream of the transfer member and upstream of the developing device with respect to a movement direction of a surface of the image bearing member and contacting the image bearing member at a contact portion, wherein the surface of the image bearing member passed through a transfer portion reaches the contact portion without being cleaned, a detecting portion for detecting a size of the sheet; and a controller for executing an operation in a cleaning mode for cleaning the contact member. The controller executes the operation in the cleaning mode when the controller discriminates that the size of the sheet detected by the detecting portion is smaller than a size of the toner image.