# US 12,761,591 B2 · Fixing device and image forming apparatus provided therewith > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,761,591 B2 - Document ID: US12761591B2 - Status: Granted - Kind: B2 - Application number: 19/081,034 - Filed: 2025-03-17 - Published: 2025-09-25 - Granted: 2026-10-13 - Earliest claimed: 2024-03-22 - Assignees: KYOCERA Document Solutions Inc. - Applicants: KYOCERA Document Solutions Inc. - Inventors: Shoko Gon; Yasuhito Okajima - Web page: https://patentgrep.com/patent/US12761591B2 ## CPC - G03G 15/2053: {Structural details of heat elements, e.g. structure of roller or belt, eddy current, induction heating} - G03G 21/206: {Conducting air through the machine, e.g. for cooling, filtering, removing gases like ozone} - G03G 15/2017: {Structural details of the fixing unit in general, e.g. cooling means, heat shielding means (G03G15/2053 takes precedence)} - G03G 15/2064: {combined with pressure} - G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY ## Abstract A fixing device includes an endless fixing belt, a fixing roller, a pressing member, and a heating unit. The heating unit includes a coil, a bobbin, an arch core, an arch core holder, and a cover. The cover covers the arch core holder from outward in the radial direction and forms an axially extending gas flow passage between the cover and the arch core holder. The cover has a pair of first opening portions disposed in opposite end parts of it along the axial direction and a second opening portion disposed in a middle part of it along the axial direction. An airflow entering the flow passage through one of the first and second opening portions circulates along the axial direction and is discharged through the other. ## Claims ### Claim 1 A fixing device comprising: a fixing belt that is endless and that is rotatable along a conveyance direction of a recording medium; a pressing member that is pressed against a fixing roller across the fixing belt under a predetermined pressure to form a fixing nip portion between the pressing member and the fixing belt; and a heating unit that heats the fixing belt, wherein the heating unit includes: a coil that extends along an axial direction along which a rotation axis of the fixing roller extends with respect to an axis of rotation of the fixing belt; a bobbin that is disposed between the coil and the fixing belt, the bobbin holding the coil; an arch core that covers the coil from outward in a radial direction orthogonal to the rotation axis of the fixing roller and extends in a circumferential direction about the rotation axis of the fixing roller, a plurality of the arch cores being arranged in a row along the axial direction; an arch core holder that holds the arch cores from outward in the radial direction; and a cover that covers the arch core holder from outward in the radial direction, the cover forming a gas flow passage between the cover and the arch core holder, the gas flow passage extending along the axial direction, the cover has a pair of first opening portions disposed in opposite end parts along the axial direction and a second opening portion disposed in a middle part along the axial direction, the pair of first opening portions and the second opening portion are arranged in a row along the axial direction on a same plane, and an airflow entering the flow passage through one of the first and the second opening portions circulates along the axial direction and is discharged through the other of the first and the second opening portions. ### Claim 2 (depends on 1) The fixing device according to claim 1, further comprising: a blower that sends gas to inside the cover, wherein the blower communicates with the first or second opening portion via a duct. ### Claim 3 (depends on 1) The fixing device according to claim 1, wherein one of the first and the second opening portions that serves as an intake port for the airflow has a guide portion for adjusting a direction of the airflow, the guide portion is in a form of a plate, the guide portion being inclined, as it extends toward the arch core holder, toward the other of the first and the second opening portions through which the airflow is discharged. ### Claim 4 (depends on 3) The fixing device according to claim 3, wherein the guide portion is formed by bending part of the cover. ### Claim 5 (depends on 1) The fixing unit according to claim 1, wherein the heating unit further includes an inner duct including a partition wall in a form of a plate dividing the flow passage, the partition wall stands upright in the radial direction and extends along the axial direction on a section perpendicular to the axial direction. ### Claim 6 (depends on 5) The fixing device according to claim 5, wherein the arch core holder has a through hole that penetrates through between the arch cores that are adjacent along the axial direction, and the inner duct has a duct bottom wall portion disposed on the arch core holder and covering part of the through hole. ### Claim 7 (depends on 1) An image forming apparatus comprising: the fixing device according to claim 1; and an image forming portion that forms an image on the recording medium. ### Claim 8 A fixing device comprising: a fixing belt that is endless and that is rotatable along a conveyance direction of a recording medium; a pressing member that forms a fixing nip portion between the pressing member and the fixing belt; and a heating unit that heats the fixing belt, wherein the heating unit includes: a coil that extends along a direction orthogonal to a conveyance direction of the recording medium; a bobbin that is disposed between the coil and the fixing belt, the bobbin holding the coil; an arch core that extends so as to stride over the coil, a plurality of the arch cores being arranged in a row along a longitudinal direction of the coil; an arch core holder that holds the arch cores from outward; and a cover that covers the arch core holder from outward, the cover forming a gas flow passage between the cover and the arch core holder, the gas flow passage extending along the longitudinal direction of the coil, the cover has a pair of first opening portions disposed in opposite end parts of the coil along the axial direction and a second opening portion disposed in a middle part of the coil along the axial direction, the pair of first opening portions and the second opening portion are arranged in a row along the longitudinal direction of the coil, and an airflow entering the flow passage through one of the first and the second opening portions circulates along the longitudinal direction of the coil and is discharged through the other of the first and the second opening portions.