Abstract: An image forming apparatus includes a control circuit for controlling amounts of heat transfer of a fixing roller and a pressure roller such that (Q1?Q0)/Hc?11 (more preferably, ?0) is satisfied where Q0 represents total amounts (J) of heat that the fixing roller and the pressure roller have during standby or just after completion of warm-up, Q1 represents total amounts (J) of heat that the fixing roller and the pressure roller have and that are saturated as a result of continuously fixing unfixed images onto recording materials and the heat amounts that the fixing roller and the pressure roller have are saturated, and Hc represents a heat capacity (J/° C.) of the fixing roller and the pressure roller.

Abstract: Comparisons are made independently for a controlled target temperature and a detected temperature of an endless belt, and a controlled target temperature and a detected temperature of a fixing roller. The operation of a halogen lamp installed in an external heating section is controlled based on results of these comparisons. This allows a temperature of the fixing member to be controlled more appropriately in a fixing apparatus that includes an external heating section for heating the fixing member.

Abstract: A fixing apparatus includes: a fixing roller which has a halogen lamp and an elastic layer therein, the elastic layer being located close to an outer surface of the fixing member; a pressure roller which is pressed against the fixing roller so that a fixing nip area is provided between the pressure roller and the fixing roller, the fixing nip area causing a toner image formed on a recording paper P to be fixed thereon; and an external heating device which has a halogen lamp and is disposed on the outer surface of the fixing member so that a second nip area is provided between the external heating device and the fixing member.

Abstract: For start of rotation of a fixing roller that is not currently being rotated, a control device causes a halogen lamp to heat an endless belt until a thermistor detects that a surface temperature of the endless belt has reached a first target temperature set at a temperature at which the endless belt is softened and is restored to its normal shape, from a deformed shape that the endless belt had while it was not rotated, to such an extent that the endless belt will never cause any rotation trouble during the rotation. This prevents the rotation trouble of the belt in a fixing apparatus in which a fixing member is heated by bringing the thus heated belt into contact with the fixing member.

Abstract: In a fixing apparatus which is included in an image forming apparatus that is capable of selecting a sheet transport speed, a paper sheet is transported between a fixing roller and a pressure roller, so that an unfixed image formed on the paper sheet is fixed on the paper sheet under heat of the fixing roller. The fixing apparatus is provided with an endless belt which heats the outer surface of the fixing roller by external contact with the outer surface of the fixing roller, and a halogen lamp, a heat source control device, and a thermistor all of which are for changing a temperature of the endless belt in accordance with the sheet transport speed. This makes it possible to fix an image on a paper sheet without the occurrence of offset phenomena.

Abstract: In an external heating type induction heating device in which a magnetic field producing means is arranged in the outer circumferential portion of a heating roller 1, two heat generating layers, namely a conductive shaft 1a and a surface heat generating layer 1c, are provided in the heating roller 1, and the surface heat generating layer 1c is formed having a thickness through which passes a portion of an alternating magnetic field, and the conductive shaft 1a at a center of the heating roller 1 is heated by a portion of the alternating magnetic field produced by the magnetic field producing means passing through the surface heat generating layer 1c to link to the conductive shaft 1a present at the center of the roller, thereby preventing a drop in a surface temperature of the heating roller 1.

Abstract: A heating roller is constituted by an elastic roller AA in which an elastic thermal insulation layer is formed, and an endless cylindrical member BB in which a releasing layer is formed on a thin-film base material (heat generating layer), wherein the elastic roller M and the cylindrical member BB are constituted such that they are separable, and wherein a slight gap is formed between the elastic roller AA and the cylindrical member BB. Then, when a fixing device is started up and the heating roller is rotated, a deflection B1 of the cylindrical member BB caused by the inner diameter difference between the cylindrical member BB and the elastic roller M is generated on the paper entry side.

Abstract: The fixing apparatus which acts as a heating apparatus, includes a heating roller; a pressure-applying roller, arranged face to face with the heating roller, for allowing a recording sheet to be conveyed by the heating and pressure-applying rollers as nipped therebetween; and a heating device for heating the heating roller. The heating roller has a first elastic layer made of an elastic material, a conductive layer disposed in the outer periphery of the first elastic layer, an elasticity-imparted second elastic layer disposed in the outer periphery of the conductive layer, and a peeling layer disposed in the outer periphery of the second elastic layer. The conductive layer of the heating roller is induction-heated by the heating device, thereby reducing the warm-up time. By providing the second elastic layer, adequate elasticity is imparted to the heating roller's surface. The toner image on the recording sheet excels in fixability and gloss property.

Abstract: The fixing apparatus which acts as a heating apparatus, includes a heating roller; a pressure-applying roller, arranged face to face with the heating roller, for allowing a recording sheet to be conveyed by the heating and pressure-applying rollers as nipped therebetween; and heating means for heating the heating roller. The heating roller has a first elastic layer made of an elastic material, a conductive layer disposed in the outer periphery of the first elastic layer, an elasticity-imparted second elastic layer disposed in the outer periphery of the conductive layer, and a peeling layer disposed in the outer periphery of the second elastic layer. The conductive layer of the heating roller is induction-heated by the heating means, thereby reducing the warm-up time. By providing the second elastic layer, adequate elasticity is imparted to the heating roller's surface. The toner image on the recording sheet excels in fixability and gloss property.

Abstract: A roller-shaped heater includes: a cylindrically formed roller member; and a heat generator disposed on the inner peripheral surface of the roller member and composed of a heat-resisting insulation material and resistance heating elements formed on the heat-resisting insulation material, and is constructed in such a manner that the heat generator is composed of a multiple number of separated portions extending in the axial direction of the cylinder of the roller member and each portion has the resistance heating element. Alternatively, the roller-shaped heater is constructed in such a manner that the heat generator is formed with a multiple number of resistance heating elements and the multiple number of resistance heating elements are arranged in parallel with each other in the axial direction of the cylinder of the roller member.