A fixing device includes a fixing member, a pressurizing member, a charging portion, and a control portion. The fixing member rotates while being heated. The pressurizing member forms a nip portion between itself and a surface of the fixing member in such a way as to hold a sheet therebetween and conveys the sheet by rotating together with the fixing member, wherein an image of toner has been formed on the sheet. The charging portion electrically charges the surface of the fixing member to a polarity that is same as a charging polarity of the toner by supplying a charging current to a pair of electrodes that is disposed to face the surface of the fixing member. The control portion acquires sheet information that includes one or more of length information, width information, and thickness information of the sheet and adjusts the charging current based on the sheet information.

A heater includes an insulator substrate, a heat generating section in which a plurality of divided regions are formed in a longitudinal direction on a first surface of the insulator substrate, electrodes formed at both end portions of the heat generating section to correspond to the plurality of divided regions, and electric conductors connected to at least one of the electrodes and formed over a surface different from the first surface of the insulator substrate.

A device includes a rotator having a rotation axis, a belt, a belt support surrounded by the belt, and a sliding sheet configured to be pinched at the nip between an inner peripheral surface of the belt and the belt support. The belt support is configured to form a nip with the rotator. One of the belt support and the sliding sheet includes a hook engaging portion. The hook engaging portion includes an aperture. The other of the belt support and the sliding sheet includes a hook engaged to the aperture.

A fusing device includes an annular belt, a heat generation member arranged inside the annular belt, and a heat transmission member that has first and second faces, wherein the first face opposes the heat generation member and the second face opposes the annular belt, and the heat transmission member transmits heat to the annular belt, wherein the heat transmission member satisfies the following Conditional Expression (1):
D/L≥0.18×S−28  (1) where D means a thermal diffusivity [×10.sup.−6 m.sup.2/s] that is determined along the first face of the heat transmission member, L means a half of an interval [×10.sup.−3 m] between two of the heat generation parts adjacent to one another, and S: the carrying speed [×10.sup.−3 m/s] at which the medium is carried.

An image forming system comprising: an apparatus main body equipped with an image forming portion, and a control portion that controls a fixing operation of fixing the image on the recording material, wherein a first fixing unit having a first heater and a first number of first temperature detection elements that detect the temperature of the first heater and a second fixing unit having a second heater and a second number of second temperature detection elements that detect the temperature of the second heater, can be selectively mounted on the apparatus main body, and the control portion controls the fixing operation on the basis of first temperature information detected by the first temperature detection elements when the first fixing unit is mounted, and controls the fixing operation on the basis of second temperature information detected by the second temperature detection elements when the second fixing unit is mounted.

An image processing apparatus includes a fixing unit including a fixing belt, and a heater configured to heat the fixing belt and including a substrate and a heating layer that is formed on the substrate, and a controller configured to, upon detecting an absence of a current flowing through the fixing belt, control the heater to not generate heat.

A heating device for an image forming unit includes a heater unit, a cylindrical film, a support member, a first heat transfer unit, and a second heat transfer unit. The cylindrical film is at least partially disposed around the heater unit. The support member is configured to support the heater unit above the cylindrical film and such that the heater unit is located between the support member and the cylindrical film. The first heat transfer unit is disposed between the cylindrical film and the heater unit and in confronting relation with a first surface of the heater unit. The first heat transfer unit has a first contact area with the heater unit. The second heat transfer unit is disposed between the heater unit and the support member and in confronting relation with a second surface of the heater unit. The second surface is opposite the first surface.

An image heating apparatus includes an image heating portion including a heater, a tubular film having an inner surface in contact with the heater, and a pressure member that is in contact with the outer surface of the film and forms a nip portion for conveying a recording material between the outer surface and the pressure member. The image heating portion heats an unfixed toner image on the recording material by the heater. A temperature detection portion detects the temperature of the heater. A control portion controls electric power to the heater such that the temperature detected by the temperature detection portion is maintained at a predetermined control target temperature. An obtainment portion obtains image information for forming the unfixed toner image. The control target temperature is set, based on the image information, for each of a plurality of regions defined by dividing the recording material in the conveying direction.

A pressing device includes a first pressurization unit; a second pressurization unit that is provided to face the first pressurization unit, and sandwiches and pressurizes a medium moving in a contact region formed between the first pressurization unit and the second pressurization unit; and a contact region variable unit that changes a width dimension of the contact region along a moving direction of the medium in a state of maintaining a contact pressure on an outlet side of the contact region, in varying a contact state of the contact region.

An image processing apparatus includes a fixing unit including a fixing belt, and a heater configured to heat the fixing belt and including a substrate and a heating layer that is formed on the substrate, and a controller configured to, upon detecting an absence of a current flowing through the fixing belt, control the heater to not generate heat.