US 12,455,523 B2
Fixing rotating member, fixing device, electrophotographic image forming apparatus, and method for manufacturing fixing rotating member
Makoto Souma, Kanagawa (JP); Matsutaka Maeda, Kanagawa (JP); Akira Okano, Kanagawa (JP); Naoko Kasai, Kanagawa (JP); and Takaaki Tsuruya, Shizuoka (JP)
Assigned to Canon Kabushiki Kaisha, Tokyo (JP)
Filed by CANON KABUSHIKI KAISHA, Tokyo (JP)
Filed on Oct. 20, 2023, as Appl. No. 18/490,924.
Claims priority of application No. 2022-171565 (JP), filed on Oct. 26, 2022.
Prior Publication US 2024/0168420 A1, May 23, 2024
Int. Cl. G03G 15/20 (2006.01); H05B 6/38 (2006.01)
CPC G03G 15/2057 (2013.01) [H05B 6/38 (2013.01); H05B 2206/022 (2013.01)] 9 Claims
OG exemplary drawing
 
1. A fixing device comprising:
a fixing rotating member; and
an induction heating device that causes the fixing rotating member to generate heat by induction heating,
wherein the fixing rotating member comprises a base material and an electro-conductive layer on the base material,
wherein the electro-conductive layer comprises heat generating rings, which are electrically connected in a circumferential direction of an outer peripheral surface of the base material and electrically divided in a longitudinal direction, and which are aligned in the longitudinal direction,
wherein the electro-conductive layer comprises silver,
wherein an average crystal grain size of crystals of the silver observed in a cross section along a circumferential direction of the electro-conductive layer is 20 to 200 nm,
wherein the electro-conductive layer has a volume resistivity of 1.0×10−8 to 8.0×10−8 Ω·m, and
wherein the induction heating device comprises:
an excitation coil that is arranged inside the fixing rotating member and has a helical portion with a helical axis substantially parallel to a direction along a rotation axis of the fixing rotating member, the excitation coil serving to form an alternating magnetic field for causing the electro-conductive layer to generate heat by electromagnetic induction; and
a magnetic core arranged in the helical portion and extending in the rotation axis direction so as not to form a loop outside the fixing rotating member, the magnetic core serving to guide lines of magnetic force of the alternating magnetic field,
wherein the magnetic core is made of a ferromagnetic material, and
wherein heat is mainly generated in the electro-conductive layer by an induced current induced by lines of magnetic force that exit from one longitudinal end of the magnetic core, pass outside the electro-conductive layer, and return to the other longitudinal end of the magnetic core.