Fixing device and image forming apparatus incorporating same

Patent metadata

Field	Value
Publication number	US-9964904-B2
Application number	US-201414226110-A
Country	US
Kind code	B2
Filing date	Mar 26, 2014
Priority date	Apr 12, 2013
Publication date	May 8, 2018
Grant date	May 8, 2018

Abstract

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.

First claim

What is claimed is:

1. A fixing device comprising:
a fixing member including a heat-generating layer; and
an induction heater configured to inductively heat the fixing member,
the induction heater including:
an excitation coil facing an outer circumferential surface of the fixing member and configured to generate a magnetic flux;
a ferromagnetic core assembly containing an arch-core facing the outer circumferential surface of the fixing member with the excitation coil interposed therebetween;

a side core facing the fixing member and contacting the arch core, the side core being configured to form a magnetic path to direct the magnetic flux generated by the excitation coil to the fixing member, the side core having a non-planar surface; and
a holder configured to hold the excitation coil and the ferromagnetic core assembly, wherein:
the side core is insert-molded in and at least partially covered by the holder,
the holder includes a plurality of spherical marks created by a plurality of stabilizing members each having a spherical tip,
the spherical tip of the plurality of stabilizing member is in contact with the non-planar surface of the side core,
the holder has three or more spherical marks on each of at least two sides of the side core, and
one of the three or more spherical marks is at a center of the holder in a longitudinal direction thereof and two of the three or more spherical marks are at both ends of the holder in the longitudinal direction thereof;

the holder having an uncovered portion at which the side core and the arch core contact each other;
wherein a diameter of an open portion of one of the spherical marks by the holder is greater than the diameter of the open portion of the one of the spherical marks by the side core; and
wherein the plurality of spherical marks are between a plurality of arch cores.

2. The fixing device according to claim 1 , wherein each of the plurality of spherical marks has a hole therein at which the ferromagnetic core is exposed.

3. The fixing device according to claim 1 , wherein the ferromagnetic core has a flat shape and is insert-molded in the holder without being processed after sintering.

4. The fixing device according to claim 1 , wherein the ferromagnetic core has ends along an axial direction of the fixing member, the ends having a greater thickness than an axial center thereof.

5. An image forming apparatus comprising the fixing device according to claim 1 .

6. The fixing device according to claim 1 , wherein the side core is warped.

7. The fixing device according to claim 1 , wherein the ferromagnetic core has ends along an axial direction of the fixing member, the ends having a different thickness than an axial center thereof.

Assignees

• OKA Yuuki
• Isoe Yukari
• Hasegawa Motokazu
• Ricoh Co Ltd

Inventors

• OKA Yuuki
• Isoe Yukari
• Hasegawa Motokazu

Classifications

• G03G15/2053 Primary

  Structural details of heat elements, e.g. structure of roller or belt, eddy current, induction heating · CPC title