Ricoh Company, Ltd.

Yukari Isoe

Motokazu Hasegawa

Susumu Matsusaka

Tsuyoshi Hashiyada

Masanobu Yamagata

Shota Kobashigawa

Kenji Maeda

Yuuki Oka

Toshiki Yokoyama

Miwa Shuto

Hisashi Kawamoto

Naoko Morisawa

Kenji Taguchi

A fixing device includes a fixing member, which includes heat-generating layer, and an induction heater to inductively heat the fixing member. The induction heater includes an excitation coil disposed facing an outer circumferential surface of the fixing member to generate a magnetic flux, a ferromagnetic core assembly containing a ferromagnetic core to form a magnetic path to direct the magnetic flux generated by the excitation coil to the fixing member, and a holder to hold the excitation coil and the ferromagnetic core assembly. The ferromagnetic core is insert-molded in and covered by the holder. The holder has a plurality of spherical marks created by a plurality of stabilizing members each having a spherical tip to stabilize the ferromagnetic core in a mold.

Fixing device and image forming apparatus incorporating same

A fixing device includes a rotatable fixing member, a pressing member to contact the fixing member with pressure to form a nip between the pressing member and the fixing member, an induction heating unit serving as a heating source to heat the fixing member, and a conductive wire drawn out of the induction heating unit to be disposed outside the cover member through a hole provided substantially at a center of the cover member in a longitudinal direction of the induction heating unit. The induction heating unit includes an excitation coil, a coil holder to hold the excitation coil, and a cover member provided facing the coil holder with the coil holder interposed between the cover member and the fixing member.

Fixing device including an induction heating unit with ducting for airflow, and image forming apparatus incorporating same

A fixing device includes a rotary member comprising a heat generation layer; an excitation coil generating magnetic flux, disposed along an axial direction of the rotary member and opposite the rotary member, to heat by induction the heat generation layer; a first demagnetizing coil layered on the excitation coil and generating magnetic flux in a direction reverse to and cancel the magnetic flux that the excitation coil generates; a sheet size detector to obtain a size of a recording sheet on which an image is to be formed by passing through the rotary member; and a drive controller to control driving of the first demagnetizing coil. The drive controller drives the first demagnetizing coil after information including the sheet size information has been obtained.

Fixing device and image forming apparatus

A fixing device includes a rotary fixing member; a pressure roller pressed against the fixing member to form a nip in association with the fixing member; and an induction heater, as a heat source, to heat the fixing member. The induction heater includes an excitation coil to induction-heat the fixing member; a side core disposed along an outer circumference in a longitudinal direction of the excitation coil; and a plurality of arch-shaped cores disposed to cover the excitation coil in the longitudinal direction thereof. The arch-shaped cores include center portions corresponding to an inner side of the excitation coil and bent to the fixing member; and outer end portions extending in the direction leading to the side core without interfering with the excitation coil.

Fixing device and image forming apparatus including same

A fixing device includes a rotator having a heat generation layer, an excitation coil to inductively heat the heat generation layer, ferromagnetic cores to direct magnetic flux arising from the excitation coil to the rotator, and a holder to hold the excitation coil and the ferromagnetic cores. In the fixing device, the ferromagnetic cores include multiple cores disposed astride the excitation coil at a turning part on each end of the excitation coil in a longitudinal direction of the excitation coil.

A fixing device includes a rotatable fixing member, a pressing member, and an induction heater. The induction heater includes an excitation coil, ferromagnetic cores, and a holder. The ferromagnetic cores include multiple arch cores and multiple side cores. The multiple arch cores are disposed facing an outer surface of a heat generation layer with the excitation coil interposed therebetween. The multiple side cores are disposed outside the excitation coil in a longitudinal direction of the induction heater so as to face both ends of each of the multiple arch cores. The multiple side cores are integrally inserted in the holder. The holder includes a spacer. The spacer contains a resin material used in the holder and provided in a close-facing portion located between at least one of the multiple arch cores and at least one of the multiple side cores to form a gap.

A fixing device includes a fixing member including a heat generator and an induction heater to heat the fixing member by electromagnetic induction. The induction heater includes an excitation coil, a ferromagnetic core to form a magnetic path to direct magnetic flux arising from the excitation coil to the fixing member, and a holder to hold the excitation coil and the ferromagnetic core. The holder has a surface facing the heat generator. The surface has a plurality of slits extending parallel to a direction of rotation of the fixing member. The ferromagnetic core is coupled to the holder and covers an open bottom portion of each slit of the plurality of slits to form a plurality of bottomed grooves.

A fixing device that includes a rotary fixing member; a pressure roller configured to press against the fixing member to form a nip with the fixing member; and an induction heating unit as a heat source to heat the fixing member. The induction heating unit includes an excitation coil; a coil retainer to hold the excitation coil; and a cover member disposed opposite the coil retainer in an opposite side of the rotary fixing member, in which the cover member protrudes toward a central predetermined range of the excitation coil in an axial direction of the rotary fixing member to effectively cool the fixing device. The induction heating unit further includes a rectifying member to effectively cool the fixing device.

A fixing device comprises a fixing member having a heat generation layer, an excitation coil disposed opposite an outer circumferential surface of the fixing member to cause the fixing member to induce electromagnetic heat, and a magnetic core to form a continuous magnetic path guiding a magnetic flux generated by the excitation coil to the fixing member. A holder is provided to accommodate and hold the excitation coil and the magnetic core. A first core included in the magnetic core and is arranged opposite the outer circumferential surface of the fixing member not via the excitation coil along a line extended from an axis of the fixing member in a radius direction. An end face of the first core arranged opposite the outer circumferential surface of the fixing member is substantially perpendicular to the line.

Fixing device employing electromagnetic induction heating system capable of effectively using magnetic flux and image forming apparatus with fixing device

A fuser includes a cylindrical heating rotating body including a heat generator and a pressure rotating body including a circumferential face which has contact with the heating rotating body to form a nip portion for fusing, wherein a disk-like outside plate, which is exposed outside, is provided in one end or both ends of the heating rotating body in a rotation axis direction, a disk-like inside plate is provided in an inner circumferential face of the heating rotating body on an inside of the outside plate to have an interval relative to the outside plate, a center vent is provided near a center of the outside plate, an outer edge vent is provided in an outer edge or the neighborhood thereof of the outside plate, and a flow path, which connects the center vent and the outer edge vent, is provided between the outside vent and the inside vent.

Fuser and image-forming apparatus

An induction heating-type fixing device includes a fixing member, an excitation coil, a magnetic core, a holder, and a pressing member. The fixing member includes a heat generating layer to heat and fuse a toner image on a recording medium. The excitation coil wound a predetermined number of times is disposed facing an outer surface of the fixing member, to generate a magnetic flux relative to the fixing member. The magnetic core forms a continuous magnetic path to direct the magnetic flux generated by the excitation coil to the fixing member. The holder holds the excitation coil and the magnetic core. The pressing member is disposed opposite the fixing member to press against the fixing member and form a fixing nip between the fixing member and the pressing member through which the recording medium is conveyed. The magnetic core is exposed from the holder at the fixing member side.

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Kanagawa, Japan

Yukari Isoe