An image heating apparatus includes an endless belt, a temperature raising portion, a first detecting portion configured to detect the temperature of the endless belt at a widthwise central portion, a controller configured to control energization to the temperature raising portion depending on an output of the first detecting portion, a second detecting portion configured to detect the temperature of the endless belt at a widthwise one end portion, an air blowing portion configured to blow air depending on an output of the second detecting portion to cool the widthwise one end portion of the endless belt, and a discriminating portion configured to discriminate whether or not the endless belt is broken on the basis of the output of the second detecting portion when the air blowing portion is operated while effecting the energization to the temperature raising portion.

An image forming apparatus includes an image forming device to transfer an image to a recording sheet; a fixing device to feed the recording sheet and fix the image onto the recording sheet; a branching device to switch between an ejection path to eject the recording sheet fed downstream of the fixing device, to outside the apparatus, and a reversing path for duplex printing; and a back curl correction structure disposed in a sheet feeding path between the fixing device and the branching device. The back curl correction structure includes a drive roller; a driven roller; an auxiliary nip portion; a guide member; and a guide moving device to move the guide member to a first position and a second position depending on the condition of the recording sheet.

A fixing device has a flexible endless fixing member; a heater to heat the fixing member; a nip forming member to contact the fixing member directly or via a slide member; a pressure member, rotatably disposed opposite the fixing member and the nip forming member; and a back curl correction structure that includes a drive roller disposed on a side where a back curl appears in the recording sheet; a driven roller disposed opposite the drive roller; an auxiliary nip portion to feed the recording sheet; a guide member to guide the recording sheet fed out from the auxiliary nip portion to bend in a direction opposite a curled direction of the back curl of the recording sheet. A driving connection between the drive roller and the pressure member is performed by a connection between a drive roller side connection gear and a pressure member side connection gear.

A positional relationship between a photosensitive drum and an intermediate transfer belt during a period from the start of the driving of the photosensitive drum to the start of image formation, or during a period of the end of the image formation to the stop of the driving of the photosensitive drum enters a separating state in a case where the image formation is executed when the process speed is a first speed, and enters a contacting state in a case where the image formation is executed when the process speed is a second speed.

An image forming apparatus may comprise the following elements. A stacking unit in which a sheet is stacked. A conveyance unit conveys the sheet. A time-counting unit counts a conveyance time from when the conveyance unit starts to convey the sheet until the sheet arrives at a predetermined position on a conveyance path. A determination unit determines that over stacking has occurred, if the conveyance time of the sheet exceeds a first over stacking threshold value.

A multilayered blade made of an elastic material includes an edge layer, having a contact edge to contact an object, and at least one backup layer laminated on the edge layer. The blade has a converted loss tangent tan δ of 0.23 or greater and 0.51 or smaller in a temperature range of from 0° C. to 50° C. The converted loss tangent tan δ is defined as: $X=\frac{A}{A+B}\times L_1+\frac{B}{A+B}\times L_2,$ where X represents the converted loss tangent tan δ, A represents a thickness in millimeters of the edge layer, B represents a thickness in millimeters of the at least one backup layer, L.sub.1 represents a variation of a loss tangent tan δ of the edge layer in the temperature range of from 0° C. to 50° C., and L.sub.2 represents a variation of a loss tangent tan δ of the at least one backup layer in the temperature range of from 0° C. to 50° C.

An relay connector fitting structure has a connector, a relay connector, and a chassis. The relay connector is removably fitted with the connector. The chassis has a fitting surface. The chassis has, formed integrally with it, a first stopper restricting movement of the relay connector in a first direction, a second stopper restricting movement of the relay connector in a second direction, and an opposite surface stopper restricting movement of the relay connector to the side opposite from the fitting surface.

An image processing apparatus includes: a first inverter to output binary image data having first resolution, as image data having pixel values that are inverted or image data having unprocessed pixel values, in accordance with an inversion signal; a thinning processor to convert the image data output from the first inverter from the first resolution to second resolution and perform a thinning process of thinning pixels of edge portions of the image data in units of the second resolution; and a second inverter to output the image data having the second resolution for which the thinning process is performed, as image data having pixel values that are inverted or image data having unprocessed pixel values, in accordance with the inversion signal.

An image forming apparatus includes a charging roller and a developing voltage application portion. The charging roller is in contact with a rotating image carrier to charge the image carrier. The developing voltage application portion applies a developing bias voltage including an AC component to a developing roller in a developing portion, when the image carrier is in a rotation state with no image. The rotation state with no image indicates a state in which the charged image carrier rotates with no electrostatic latent image being formed thereon. The developing portion supplies toner containing an external additive to the image carrier.

An image forming apparatus includes: a fixing part including a heater, and a first temperature detection part configured to detect the temperature of the heater; a chopper circuit including a reactor, a freewheeling element, and a switching element, the chopper circuit being configured to switch an input direct current on and off in a specified duty cycle by using the switching element and to supply the current to the heater; and a control part configured to control the duty cycle based on a detection result obtained by the first temperature detection part, as well as to control a switching frequency of the switching element based on an operation mode of the image forming apparatus.