An image forming apparatus includes: an apparatus main body to which a fixing device that thermally fixes a toner image on a sheet is detachably mounted; a controller that performs authentication of a user using the image forming apparatus, and controls the image forming apparatus; and a storage that stores user information indicating availability of replacement work of the fixing device by the user, wherein the controller determines availability of replacement work of the fixing device by the user, based on the user information at a time of usage by the authenticated user, and inquires the user whether to perform replacement of the fixing device according to a determination result.

An image forming apparatus of the present invention includes a circuit including both a circuit within a fixing unit and a power control circuit, provided with a first circuit which supplies power to a heater from an AC power supply, a second circuit electrically insulated from the first circuit, and a third circuit electrically insulated from both the first circuit and the second circuit, all of the first to third circuits are provided on at least one surface of a circuit board, and the first to third circuits are disposed on at least one straight line on which all of the first to third circuits are present on the one surface of the circuit board in the order of the first circuit, the third circuit and the second circuit.

An image forming apparatus with a detachable fixing device that is capable of printing with high quality without printing wastefully. A storage unit stores identification information about a fixing device in association with an attribute of a sheet that is printable with the fixing device concerned. A control unit executes printing when the storage unit does not store an attribute of a sheet corresponding to a fixing device that is currently attached to the image forming apparatus. The control unit determines whether to execute printing according to an attribute of a sheet used in printing and an attribute of a sheet stored in the storage unit when the storage unit stores the attribute of the sheet corresponding to the fixing device that is currently attached to the image forming apparatus.

An image forming apparatus with a detachable fixing device that is capable of printing with high quality without printing wastefully. A storage unit stores identification information about a fixing device in association with an attribute of a sheet that is printable with the fixing device concerned. A control unit executes printing when the storage unit does not store an attribute of a sheet corresponding to a fixing device that is currently attached to the image forming apparatus. The control unit determines whether to execute printing according to an attribute of a sheet used in printing and an attribute of a sheet stored in the storage unit when the storage unit stores the attribute of the sheet corresponding to the fixing device that is currently attached to the image forming apparatus.

An image forming apparatus with a detachable fixing device that is capable of printing with high quality without printing wastefully. A storage unit stores identification information about a fixing device in association with an attribute of a sheet that is printable with the fixing device concerned. A control unit executes printing when the storage unit does not store an attribute of a sheet corresponding to a fixing device that is currently attached to the image forming apparatus. The control unit determines whether to execute printing according to an attribute of a sheet used in printing and an attribute of a sheet stored in the storage unit when the storage unit stores the attribute of the sheet corresponding to the fixing device that is currently attached to the image forming apparatus.

A fixing apparatus fixes an image onto a recording material. A first fuse and a second fuse are connected in series each other. A power supply line is connected to one end of the first fuse. A signal line is connected to a connection point between another end of the first fuse and one end of the second fuse. A ground line is connected to another end of the second fuse. Information regarding the fixing apparatus is held in accordance with melt states of the first and second fuses.

An image forming apparatus includes an apparatus main assembly having a door, a feeding unit including first and second rotatable members configured to form a nip for feeding a sheet and a moving mechanism configured to move the first rotatable member in a spacing direction relative to the second rotatable member, a power source provided in the apparatus main assembly, and a motor provided in the apparatus main assembly and configured to drive the moving mechanism. The feeding unit is detachably mountable to the apparatus main assembly upon opening of the door. An electric power supplying path is capable of supplying electric power from the power source to the motor via the feeding unit despite the door being in an open state.

A fixing apparatus fixes an image onto a recording material. A first fuse and a second fuse are connected in series each other. A power supply line is connected to one end of the first fuse. A signal line is connected to a connection point between another end of the first fuse and one end of the second fuse. A ground line is connected to another end of the second fuse. Information regarding the fixing apparatus is held in accordance with melt states of the first and second fuses.

A removable unit that is attachable to and detachable from a body of an apparatus includes a positioning projection and an upstream projection. The positioning projection projects downward to position a unit or a member located below the removable unit when the removable unit is attached to the body. The upstream projection projects more downward than the positioning projection at an upstream end of the removable unit in an attachment direction of the removable unit to the apparatus. A lower end of the positioning projection is located higher than a line connecting a lower end of the upstream projection and a lower portion of a downstream end of the removable unit in the attachment direction when viewed in a direction orthogonal to both an up and down direction and the attachment direction.

An image forming apparatus comprises a fixing device comprising a heater for heating a sheet on which an image is formed and a non-volatile memory in which characteristic information of the heater is stored. The fixing device is replaceable. In a case where the fixing device is replaced, the image forming apparatus starts to supply power to the heater before completing to read the characteristic information from the fixing device replaced. Due to this, the image forming apparatus can promptly heat the heater of the fixing device than before.