Patent ID: 9429887
Filing Date: 2016-08-30
CPC Classification: G03G,H05B

Claim Text:
1. A fixing device comprising: a housing; a magnetic flux generation source fixed to the housing and configured to generate a magnetic flux; a first rotary body configured to be rotated in a predetermined direction and induction-heated by the magnetic flux; a second rotary body configured to be rotated in a predetermined direction, a nip portion through which a sheet carrying a toner image passes being formed between the first and second rotary bodies; a first core made of a magnetic material and configured to form a magnetic path, along which the magnetic flux passes, together with the first rotary body; a second core made of a magnetic material, arranged between the first core and the first rotary body when viewed from the magnetic path and rotatable in a predetermined direction; a shaft portion having a hollow cylindrical shape, configured to hold the second core on a peripheral surface, including an internal space extending along an axial direction inside and serving as a rotary shaft in the rotation of the second core; a magnetic shielding body made of a nonmagnetic material, arranged on a peripheral surface of the second core or the shaft portion and configured to shield or suppress the magnetic flux by being located in the magnetic path with rotation about the shaft portion; and an air flow generator configured to generate an air flow flowing in the internal space from one end side toward the other end side in the axial direction; an introducing portion mounted on one end side of the shaft portion in the axial direction and configured to introduce the air flow into the internal space; a driving portion for generating a rotational drive force for rotating the shaft portion; and a transmitting portion coupled to the driving portion and mounted on the other end side of the shaft portion in the axial direction and configured to transmit the rotational drive force to the shaft portion, the transmitting portion including a communication space communicating with the internal space and an exhaust port communicating with the communication space and open on an outer peripheral surface of the transmitting portion, wherein the magnetic flux generation source being fixed to the housing to surround the second core extending in the axial direction when viewed in a direction perpendicular to the axial direction; the second core includes: the magnetic shielding body is arranged at least in the same areas as the outer core portions in the axial direction to cover areas of the second core or the shaft portion different from exposed areas in the circumferential direction, and the introducing portion is made of a hollow cylindrical heat resistant material communicating with the internal space and includes a bearing member configured to rotatably support the one end side of the shaft portion and an introducing tube mounted on the bearing member and configured to introduce the air flow toward the internal space via the bearing member.