Abstract: An image heating device includes, a moving member configured to move while contacting a recording material at one surface of the moving member, a backup member configured to contact the other surface of the moving member, a holding member configured to hold the backup member, a nip portion forming member contacting the one surface of the moving member, and configured to form a nip portion in corporation with the backup member via the moving member, and a high thermal conductive member held between the holding member and the backup member, wherein the recording material on which an image has been formed is heated by heat received from the moving member while being nipped and conveyed at the nip portion, and wherein the holding member includes a recessed portion configured not to apply pressure to the high thermal conductive member.

Abstract: An image heating apparatus includes: a heater including a substrate and a heat generating element; a supporting member; a high heat-conductive member. The recording material on which an image is formed is heated by heat from the heater. The supporting member has a bottom region, where the supporting member supports the heater, including a first region where the supporting member contacts the high heat-conductive member so as to apply pressure between the heater and the high heat-conductive member and including a second region where the supporting member is recessed from the high heat-conductive member relative to the first region. At least a part of the first region overlaps, with respect to a movement direction of the recording material, with a region where the heat generating element is provided.

Abstract: A heater used for a fixing device includes a substrate, first and second conductor patterns formed at either end of the substrate in the short direction of the substrate, a third conductor pattern formed between the first and second conductor patterns and separated from the two conductor patterns, a first heating member disposed between the first and third conductor patterns and electrically connected to the two conductor patterns, and a second heating member disposed between the second and third conductor patterns and electrically connected to the conductor patterns. The heater has both end regions in which the widths of the third conductor pattern in the short direction is smaller than that of a middle portion of the third conductor pattern. The widths of the first and second heating members in the end regions are smaller than the widths of the first and second heating members in the other region, respectively.

Abstract: A fixing device includes: a rotatable member; a helical coil; a magnetic core; and a controller for controlling the frequency of an AC current caused to flow through the coil. The AC current is caused to flow through the coil to cause an electroconductive layer of the rotatable member to generate heat through electromagnetic induction heating, thereby heating and fixing the toner image on the recording material by heat of the rotatable member. The controller controls the frequency in a period so that when the frequency is f and a resistance of the electroconductive layer with respect to a circumferential direction is R, f/R is substantially constant.

Abstract: An image heating apparatus includes: a heater; a supporting member for supporting the heater; and a high heat-conductive sheet sandwiched between a part of the heater and the supporting member. A recording material on which an image is formed is heated by heat from the heater. The supporting member includes a bearing surface contacting the sheet so as to apply pressure between the heater and the sheet and includes an opposing portion opposing a part of the heater not sandwiching the sheet. In a state in which the pressure is applied between the heater and the sheet, the thickness of the sheet is not less than the height of the stepped portion between the bearing portion and the opposing portion.

Abstract: An image heating apparatus includes: a heater including a substrate and a heat generating element; a supporting member; a high heat-conductive member. The recording material on which an image is formed is heated by heat from the heater. The supporting member has a bottom region, where the supporting member supports the heater, including a first region where the supporting member contacts the high heat-conductive member so as to apply pressure between the heater and the high heat-conductive member and including a second region where the supporting member is recessed from the high heat-conductive member relative to the first region. At least a part of the first region overlaps, with respect to a movement direction of the recording material, with a region where the heat generating element is provided.

Abstract: An image heating apparatus includes: a heater including a substrate and a heat generating element; a supporting member; and a high heat-conductive member. The recording material on which an image is formed is heated by heat from the heater. The supporting member has a bottom region, where the supporting member supports the heater, including a first region where the supporting member contacts the high heat-conductive member so as to apply pressure between the heater and the high heat-conductive member and including a second region where the supporting member is recessed from the high heat-conductive member relative to the first region. At least a part of the first region overlaps, with respect to a movement direction of the recording material, with a region where the heat generating element is provided.

Abstract: An image heating apparatus, to heat an image formed on a recording material includes a cylindrical rotatable member having a conductive layer, a coil having a helically shaped portion which is helically wound in a generatrix direction of the rotatable member inside the rotatable member, and a magnetic core disposed inside the helically shaped portion. The coil, which includes a number of turns, produces an alternating magnetic field to cause the conductive layer to generate heat by electromagnetic induction. The magnetic core includes a plurality of divided cores into which the magnetic core is divided in the generatrix direction. The number of turns of the coil per unit length, at a region that corresponds to a boundary between the plurality of divided cores, is larger than the number of turns of the coil at a region that corresponds to the plurality of divided cores.

Abstract: A fixing device includes: a rotatable member; a helical coil; a magnetic core; and a controller for controlling a frequency of an AC current caused to flow through the coil. The AC current is caused to flow through the coil to cause an electroconductive layer of the rotatable member to generate heat through electromagnetic induction heating thereby to heat and fix the toner image on the recording material by heat of the rotatable member. The controller controls the frequency in a period so that when the frequency is f and a resistance of the electroconductive layer with respect to a circumferential direction is R, f/R is substantially constant.

Abstract: A fixing device includes a rotatable member having an electroconductive layer; a magnetic member which does not form a loop outside the electroconductive layer; a coil helically wound outside said magnetic member, wherein the coil forms an AC magnetic field by a flow of a current therethrough to cause the electroconductive layer to generate heat through electromagnetic induction heating; and a back-up member. When a circumferential direction resistance R of the electroconductive layer is represented by the following formula (1), a frequency f of the AC magnetic field and the circumferential direction resistance R satisfy the following formula (2): R=?×2?r/tw??(1) f/R?15 (kHz/milliohm)??(2) where with respect to the electroconductive layer, ? is a volume resistivity at a fixing temperature, t is a thickness, r is a radius, and w is a length with respect to a generatrix direction of the rotatable member.

Abstract: An image heating apparatus to heat an image formed on a recording material includes a cylindrical rotatable member having a conductive layer, a coil having a helically shaped portion which is helically wound in a generatrix direction of the rotatable member inside the rotatable member, and a magnetic core disposed inside the helically shaped portion. The coil, which includes a number of turns, produces an alternating magnetic field to cause the conductive layer to generate heat by electromagnetic induction. The magnetic core includes a plurality of divided cores into which the magnetic core is divided in the generatrix direction. The number of turns of the coil per unit length, at a region that corresponds to a boundary between the plurality of divided cores, is larger than the number of turns of the coil at a region that corresponds to the plurality of divided cores.

Abstract: An image heating apparatus, which is configured to heat an image formed on a recording material, includes a cylindrical rotatable member including a conductive layer, and a coil including a helically shaped portion helically wound along a generatrix direction of the rotatable member inside the rotatable member. The coil is configured to produce an alternating magnetic field for causing the conductive layer to generate heat by electromagnetic induction. The image heating apparatus further includes a magnetic core disposed in the helically shaped portion. The magnetic core includes a plurality of divided cores into which the magnetic core is divided in the generatrix direction. The number of turns of the coil per unit length at a region that corresponds to a boundary between the divided cores is larger than the number of turns of the coil at a region that does not correspond to the boundary.

Abstract: A heater used for a fixing device includes a substrate, first and second conductor patterns formed at either end of the substrate in the short direction of the substrate, a third conductor pattern formed between the first and second conductor patterns and separated from the two conductor patterns, a first heating member disposed between the first and third conductor patterns and electrically connected to the two conductor patterns, and a second heating member disposed between the second and third conductor patterns and electrically connected to the conductor patterns. The heater has both end regions in which the widths of the third conductor pattern in the short direction is smaller than that of a middle portion of the third conductor pattern. The widths of the first and second heating members in the end regions are smaller than the widths of the first and second heating members in the other region, respectively.

Abstract: A heater used for a fixing device includes a substrate, first and second conductor patterns formed at either end of the substrate in the short direction of the substrate, a third conductor pattern formed between the first and second conductor patterns and separated from the two conductor patterns, a first heating member disposed between the first and third conductor patterns and electrically connected to the two conductor patterns, and a second heating member disposed between the second and third conductor patterns and electrically connected to the conductor patterns. The heater has both end regions in which the widths of the third conductor pattern in the short direction is smaller than that of a middle portion of the third conductor pattern. The widths of the first and second heating members in the end regions are smaller than the widths of the first and second heating members in the other region, respectively.

Abstract: A fixing device includes a rotatable member having an electroconductive layer; a magnetic member which does not form a loop outside the electroconductive layer; a coil helically wound outside said magnetic member, wherein the coil forms an AC magnetic field by a flow of a current therethrough to cause the electroconductive layer to generate heat through electromagnetic induction heating; and a back-up member. When a circumferential direction resistance R of the electroconductive layer is represented by the following formula (1), a frequency f of the AC magnetic field and the circumferential direction resistance R satisfy the following formula (2): R=?×2?r/tw ??(1) F/R?15 (kHz/m?) ??(2) where with respect to the electroconductive layer, ? is a volume resistivity, t is a thickness, r is a radius, and w is a length with respect to a generatrix direction of the rotatable member.

Abstract: An image heating apparatus, which is configured to heat an image formed on a recording material, includes a cylindrical rotatable member including a conductive layer, and a coil including a helically shaped portion helically wound along a generatrix direction of the rotatable member inside the rotatable member. The coil is configured to produce an alternating magnetic field for causing the conductive layer to generate heat by electromagnetic induction. The image heating apparatus further includes a magnetic core disposed in the helically shaped portion. The magnetic core includes a plurality of divided cores into which the magnetic core is divided in the generatrix direction. The number of turns of the coil per unit length at a region that corresponds to a boundary between the divided cores is larger than the number of turns of the coil at a region that does not correspond to the boundary.

Abstract: An image heating device includes, a moving member configured to move while contacting a recording material at one surface of the moving member, a backup member configured to contact the other surface of the moving member, a holding member configured to hold the backup member, a nip portion forming member contacting the one surface of the moving member, and configured to form a nip portion in corporation with the backup member via the moving member, and a high thermal conductive member held between the holding member and the backup member, wherein the recording material on which an image has been formed is heated by heat received from the moving member while being nipped and conveyed at the nip portion, and wherein the holding member includes a recessed portion configured not to apply pressure to the high thermal conductive member.

Abstract: An image heating apparatus includes: a heater including a substrate and a heat generating element; a supporting member; a high heat-conductive member. The recording material on which an image is formed is heated by heat from the heater. The supporting member has a bottom region, where the supporting member supports the heater, including a first region where the supporting member contacts the high heat-conductive member so as to apply pressure between the heater and the high heat-conductive member and including a second region where the supporting member is recessed from the high heat-conductive member relative to the first region. At least a part of the first region overlaps, with respect to a movement direction of the recording material, with a region where the heat generating element is provided.

Abstract: An image heating apparatus includes: a heater; a supporting member for supporting the heater; a high heat-conductive sheet sandwiched between a part of the heater and the supporting member. A recording material on which an image is formed is heated by heat from the heater. The supporting member includes a bearing surface contacting the sheet so as to apply pressure between the heater and the sheet and includes an opposing portion opposing a part of the heater not sandwiching the sheet. In a state in which the pressure is applied between the heater and the sheet, a thickness of the sheet is not less than a height of the stepped portion between the bearing portion and the opposing portion.

Abstract: A heater used for a fixing device includes a substrate, first and second conductor patterns formed at either end of the substrate in the short direction of the substrate, a third conductor pattern formed between the first and second conductor patterns and separated from the two conductor patterns, a first heating member disposed between the first and third conductor patterns and electrically connected to the two conductor patterns, and a second heating member disposed between the second and third conductor patterns and electrically connected to the conductor patterns. The heater has both end regions in which the widths of the third conductor pattern in the short direction is smaller than that of a middle portion of the third conductor pattern. The widths of the first and second heating members in the end regions are smaller than the widths of the first and second heating members in the other region, respectively.