# US 12,216,420 B2 · Image forming apparatus and control method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,216,420 B2 - Document ID: US12216420B2 - Status: Granted - Kind: B2 - Application number: 18/531,216 - Filed: 2023-12-06 - Published: 2024-03-28 - Granted: 2025-02-04 - Earliest claimed: 2022-09-13 - Assignees: Toshiba Tec Kabushiki Kaisha - Applicants: Toshiba Tec Kabushiki Kaisha - Inventors: Masaya Tanaka; Hiroshi Ota - Web page: https://patentgrep.com/patent/US12216420B2 ## CPC - G03G 15/2039: {with means for controlling the fixing temperature} - G03G 15/2042: {specially for the axial heat partition} - 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: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY ## Abstract An image forming apparatus has an image forming unit to form a toner image on a first sheet and a fixing unit configured to heat the first sheet to fix the image to the first sheet. A control unit begins a cooling process for cooling the fixing unit when an overheating condition is met, then permits the image forming unit to form a toner image on a second sheet after the cooling process ends according to a first cooling condition if a person is detected near the image forming apparatus or after the cooling process ends according to a second cooling condition if a person not detected near the image forming apparatus. The cooling process under the first cooling condition ends in less time than under the second cooling condition. ## Claims ### Claim 1 An image forming apparatus, comprising: an image forming unit configured to form a toner image on a first sheet in an image forming process; a fixing unit configured to heat the first sheet to fix the toner image to the first sheet, comprising a heater including a substrate and heating elements arranged on the substrate; and a control unit configured to: begin a cooling process for cooling of the fixing unit when an overheating condition is met after the fixing of the toner image to the first sheet, permit the image forming unit to form a toner image on a second sheet after the cooling process ends according to a first cooling condition if a person is determined to be positioned in a predetermined region in the vicinity of the image forming apparatus, and permit the image forming unit to form a toner image on the second sheet after the cooling process ends according to a second cooling condition if a person is determined not to be positioned in the predetermined region in the vicinity of the image forming apparatus, wherein the cooling process according to the first cooling condition ends in less time than the cooling process according to the second cooling condition. ### Claim 2 (depends on 1) The image forming apparatus according to claim 1, wherein the substrate is a ceramic material. ### Claim 3 (depends on 1) The image forming apparatus according to claim 1, wherein the heating elements are arranged along a traveling direction of the first sheet. ### Claim 4 (depends on 1) The image forming apparatus according to claim 1, wherein the heating elements includes a first heating element which has a longitudinal direction perpendicular to the traveling direction of the first sheet. ### Claim 5 (depends on 4) The image forming apparatus according to claim 4, wherein the heating elements includes a second heating element which has a longitudinal direction perpendicular to the traveling direction of the first sheet, and the length of the second heating element in the longitudinal direction of the second heating element is shorter than the length of the first heating element in the longitudinal direction of the first heating element. ### Claim 6 (depends on 5) The image forming apparatus according to claim 5, wherein the heating elements includes a third heating element which has a longitudinal direction perpendicular to the traveling direction of the first sheet, and the length of the third heating element in the longitudinal direction of the third heating element is shorter than the length of the second heating element in the longitudinal direction of the second heating element. ### Claim 7 (depends on 6) The image forming apparatus according to claim 6, wherein the heating elements includes a fourth heating element which has a longitudinal direction perpendicular to the traveling direction of the first sheet, and the length of the fourth heating element in the longitudinal direction of the fourth heating element is longer than the length of the second heating element in the longitudinal direction of the second heating element. ### Claim 8 (depends on 7) The image forming apparatus according to claim 7, wherein the second heating element is arranged between the first heating element and the fourth heating element along the traveling direction of the first sheet. ### Claim 9 (depends on 8) The image forming apparatus according to claim 8, wherein the third heating element is arranged between the first heating element and the fourth heating element along the traveling direction of the first sheet. ### Claim 10 (depends on 1) The image forming apparatus according to claim 1, wherein the overheating condition is a sheet passage region of the fixing unit for the second sheet being at a temperature higher than a predetermined threshold after the fixing of the toner image on the first sheet. ### Claim 11 (depends on 1) The image forming apparatus according to claim 1, wherein the overheating condition is a sheet non-passage region of the fixing unit for the second sheet being a portion of a sheet passage region of the fixing unit for the first sheet. ### Claim 12 (depends on 1) The image forming apparatus according to claim 1, wherein the overheating condition includes the first sheet being narrower in sheet width than the second sheet. ### Claim 13 (depends on 1) The image forming apparatus according to claim 1, wherein the overheating condition is a continuous printing of sheets before the second sheet being greater than a predetermined threshold number and the sheets before the second sheet being narrower in sheet width than the second sheet. ### Claim 14 (depends on 1) The image forming apparatus according to claim 1, further comprising: a human detection sensor configured to detect a person positioned in the predetermined region in the vicinity of the image forming apparatus. ### Claim 15 (depends on 14) The image forming apparatus according to claim 14, wherein the human detection sensor includes an infrared sensor. ### Claim 16 (depends on 1) The image forming apparatus according to claim 1, further comprising: an operation panel configured to receive user inputs for controlling operations of the image forming apparatus, wherein the control unit is configured to determine a person is positioned in the predetermined region in the vicinity of the image forming apparatus based on receiving of a user input at the operation panel. ### Claim 17 (depends on 1) The image forming apparatus according to claim 1, wherein the cooling process is maintaining the fixing unit in a stopped state. ### Claim 18 (depends on 17) The image forming apparatus according to claim 17, wherein the first cooling condition requires the fixing unit to be in the stopped state for a first period of time, the second cooling condition requires the fixing unit to be in the stopped state for a second period of time, and the first period of time is shorter than the second period of time. ### Claim 19 A printer, comprising: a human detection sensor configured to detect a person in a predetermined region in the vicinity of the printer; an image forming unit configured to form a toner image on a first sheet in an image forming process; a fixing unit configured to heat the first sheet to fix the toner image to the first sheet, comprising a heater including a substrate and heating elements arranged on the substrate; and a controller configured to: begin a cooling process for cooling of the fixing unit when an overheating condition is met after the fixing of the toner image to the first sheet, permit the image forming unit to form a toner image on a second sheet after the cooling process ends according to a first cooling condition if the human detection sensor detects a person in the predetermined region, and permit the image forming unit to form a toner image on the second sheet after the cooling process ends according to a second cooling condition if the human detection sensor does not detect a person in the predetermined region, wherein the cooling process according to the first cooling condition ends in less time than the cooling process according to the second cooling condition. ### Claim 20 (depends on 19) The printer according to claim 19, wherein the substrate is a ceramic material.