In one embodiment, a heating device includes a tubular body and a heater within an interior region formed by the tubular body. A first temperature detector is disposed within the interior region. A first wire is connected to the first temperature detector on a first side of the first temperature detector facing a first direction parallel to the axial length of the tubular body. A second temperature detector is disposed within the interior region on a second side of the first temperature detector opposite the first side. The second temperature detector is spaced from the first temperature detector in a second direction opposite of the first direction. A second wire is connected to the second temperature detector on a side of the second temperature detector facing the second direction. The first wire and the second wire extend with each other to an outer end of the tubular body.

According to one embodiment, a fixing device includes a belt, a heater, and a holder. The belt is formed into a cylindrical shape, is rotated in a circumferential direction to transport a sheet, and applies heat to the sheet. The heater is arranged on an inner side of the belt and extends in a predetermined longitudinal direction to heat the belt. The holder extends in the longitudinal direction of the heater and holds the heater. The holder includes a support portion and a retraction portion. The support portion comes into contact with the heater and supports the heater. The retraction portion is provided at a position avoiding the support portion in the longitudinal direction of the heater, and includes a smaller contact area with the heater than the contact area between the support portion and the heater or does not come into contact with the heater.

An image forming apparatus includes a fixing device and a control unit. The fixing device includes a heating resistor formed of a positive temperature coefficient material. The control unit energizes the heating resistor with a first energization amount if a temperature of the heating resistor is lower than a predetermined temperature, and energizes the heating resistor with a second energization amount that is higher than the first energization amount if the temperature of the heating resistor is higher than the predetermined temperature.

A fixing device includes a roller, an endless belt, and a heat generating member disposed in a space inside the endless belt, extending in a width direction of the endless belt, and pressing the endless belt against the roller. A sheet is passed through a nip formed between the roller and a portion of the endless belt pressed by the heat generating member, such that an image on the sheet is fixed thereto. The heat generating member includes first and second heat generating portions that are adjacent to each other along the width direction, and the first portion heat generating is independently operable from the second heat generating portion.

A fixing device includes a roller, an endless belt, and a heat generating member disposed in a space inside the endless belt, extending in a width direction of the endless belt, and pressing the endless belt against the roller. A sheet is passed through a nip formed between the roller and a portion of the endless belt pressed by the heat generating member, such that an image on the sheet is fixed thereto. The heat generating member includes first and second heat generating portions that are adjacent to each other along the width direction and independently operable from each other. A boundary of the first and second heat generating portions extends in a direction inclined with respect to a sheet conveying direction.

A heating device includes a cylindrical body with a hollow interior and a heater inside the hollow interior. A first surface of the heater faces the inner surface of the cylindrical body. A heat transfer member is on a second surface of the heater. A grease is between the heater and the heat transfer member. A support member is provided including a first portion fixed to the second surface of the heater and a second portion contacting a surface of the heat transfer member. The support member includes a third portion between the first and second portions. The third portion does not contact the second surface of the heater between the first and second portions and provides a space for grease from between the heater and the heat transfer member to accumulate.

A fuser unit for a hot fuse printer system includes a heating roller having a heating element which does not extend the entire length of the roller. The roller may include at least two heating elements, one of which heats a first heating zone and the other which heats a second heating zone.

An image forming apparatus including: an image forming portion that forms a toner image on a recording material; a fixing portion that has a heater unit including a heater and that fixes the toner image on the recording material, the heater being capable of changing a heat generating region; a control portion that controls the heater; and an image adding portion that adds a predetermined additional image to a desired image, wherein the control portion sets the heat generating region according to a width of the desired image in a direction perpendicular to the conveying direction or a width of the recording material in the direction perpendicular to the conveying direction, and the width of the predetermined additional image in the direction perpendicular to the conveying direction is equal to or less than the width of the heat generating region in the direction perpendicular to the conveying direction.

A heating device for heating a medium on which an image can be formed includes a cylindrical belt, a first heating unit, and a second heating unit. The first and second heating units are inside the cylindrical belt and face an inner circumferential surface of the belt. A controller is configured to control the heating units to generate heat. When the medium is to be heated to reach an image fixing temperature at which the image can be fixed to the medium, the controller controls the first and second heating units to both generate heat. After the medium is heated to the image fixing temperature, the controllers control the first heating unit to generate heat, but not the second heating unit.

In one embodiment, a heating device includes a tubular body and a heater within an interior region formed by the tubular body. A first temperature detector is disposed within the interior region. A first wire is connected to the first temperature detector on a first side of the first temperature detector facing a first direction parallel to the axial length of the tubular body. A second temperature detector is disposed within the interior region on a second side of the first temperature detector opposite the first side. The second temperature detector is spaced from the first temperature detector in a second direction opposite of the first direction. A second wire is connected to the second temperature detector on a side of the second temperature detector facing the second direction. The first wire and the second wire extend with each other to an outer end of the tubular body.