# US 2024/0201622 A1 · Control device and image forming apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2024/0201622 A1 - Document ID: US20240201622A1 - Status: Published application - Kind: A1 - Application number: 18/346,842 - Filed: 2023-07-04 - Published: 2024-06-20 - Earliest claimed: 2022-12-20 - Assignees: Toshiba Tec Kabushiki Kaisha - Applicants: Toshiba Tec Kabushiki Kaisha - Inventors: Yutaka USAMI - Web page: https://patentgrep.com/patent/US20240201622A1 ## CPC - G03G 15/205: {specially for the mode of operation, e.g. standby, warming-up, error (G03G15/2046 takes precedence)} - G03G 15/2042: {specially for the axial heat partition} - G03G 15/2064: {combined with pressure} - G03G 15/5004: {Power supply control, e.g. power-saving mode, automatic power turn-off} - G03G 15/5008: {Driving control for rotary photosensitive medium, e.g. speed control, stop position control} - G03G 2215/2045: Variable fixing speed - G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY ## Abstract A control device for controlling heat applied to a medium conveyed along a path, includes: first and second heaters arranged along a first direction crossing the path, the first heater overlapping the medium and the second heater not overlapping the medium when viewed in a direction crossing the path and the first direction; a sensor; and a circuit configured to determine estimated temperatures of the heaters based on power supplied thereto, determine a corrected temperature of the first heater based on the estimated temperature thereof and a temperature measured by the sensor, determine a corrected temperature of the second heater based on the estimated temperature thereof and the corrected and estimated temperatures of the first heater, energize the heaters based on the corrected temperatures, and issue a command for controlling a conveying speed based on the corrected temperature of the second heater. ## Claims ### Claim 1 A control device for controlling heat to be applied to a medium conveyed along a conveyance path, comprising: a plurality of heaters arranged along a first direction crossing the conveyance path, wherein the heaters include first and second heaters, wherein when the medium is conveyed, the first heater overlaps the medium and the second heater does not overlap the medium when viewed in a second direction crossing the conveyance path and the first direction; a temperature sensor; and a control circuit configured to: determine an estimated temperature of each of the first and second heaters based on an amount of power supplied to said each of the first and second heaters, determine a corrected temperature of the first heater based on the estimated temperature of the first heater and a temperature measured by the temperature sensor, determine a corrected temperature of the second heater based on the estimated temperature of the second heater, the corrected temperature of the first heater, and the estimated temperature of the first heater, generate energizing pulses for energizing the first and second heaters based on the corrected temperatures of the first and second heaters, and issue a command for controlling a conveying speed of the medium based on the corrected temperature of the second heater. ### Claim 2 (depends on 1) The control device according to claim 1, wherein the control circuit is configured to determine whether the corrected temperature of the second heater is greater than a first threshold value, and the command instructs decreasing the conveying speed when the corrected temperature of the second heater is greater than the first threshold value. ### Claim 3 (depends on 2) The control device according to claim 2, wherein the command instructs increasing the conveying speed when the corrected temperature of the second heater is not greater than the first threshold value. ### Claim 4 (depends on 1) The control device according to claim 1, further comprising: a processor configured to control the conveyance speed according to the command issued by the control circuit. ### Claim 5 (depends on 4) The control device according to claim 4, wherein the processor is configured to determine a size of the medium, the control circuit is configured to determine whether the size of the medium is smaller than a predetermined size, and the control circuit does not issue the command when the size of the medium is not smaller than the predetermined size. ### Claim 6 (depends on 1) The control device according to claim 1, wherein the control circuit determines the estimated temperature of each of the first and second heaters further based on a previously estimated temperature thereof. ### Claim 7 (depends on 1) The control device according to claim 1, wherein the control circuit determines the estimated temperature of each of the first and second heaters based on a corresponding equivalent thermal circuit. ### Claim 8 (depends on 7) The control device according to claim 7, wherein the equivalent thermal circuit for each of the first and second heaters includes a resistor representing heat dissipation by the medium, and the resistor of the equivalent thermal circuit for the first heater has a resistance value smaller than the resistor of the equivalent thermal circuit for the second heater. ### Claim 9 (depends on 1) The control device according to claim 1, wherein the first heater is located at the center of the medium when the medium is conveyed when viewed in the second direction. ### Claim 10 (depends on 1) The control device according to claim 1, wherein the heaters are disposed inside a roller for conveying the medium. ### Claim 11 An image forming apparatus comprising: a fixing device configured to fix, by heat, an image formed on a medium conveyed along a conveyance path, the fixing device including: a plurality of heaters arranged along a first direction crossing the conveyance path, wherein the heaters include first and second heaters, wherein when the medium is conveyed, the first heater overlaps the medium and the second heater does not overlap the medium when viewed in a second direction crossing the conveyance path and the first direction, and a temperature sensor; and a control circuit configured to: determine an estimated temperature of each of the first and second heaters based on an amount of power supplied to said each of the first and second heaters, determine a corrected temperature of the first heater based on the estimated temperature of the first heater and a temperature measured by the temperature sensor, determine a corrected temperature of the second heater based on the estimated temperature of the second heater, the corrected temperature of the first heater, and the estimated temperature of the first heater, generate energizing pulses for energizing the first and second heaters based on the corrected temperatures of the first and second heaters, and issue a command for controlling a conveying speed of the medium based on the corrected temperature of the second heater. ### Claim 12 (depends on 11) The image forming apparatus according to claim 11, wherein the control circuit is configured to determine whether the corrected temperature of the second heater is greater than a first threshold value, and the command instructs decreasing the conveying speed when the corrected temperature of the second heater is greater than the first threshold value. ### Claim 13 (depends on 12) The image forming apparatus according to claim 12, wherein the command instructs increasing the conveying speed when the corrected temperature of the second heater is not greater than the first threshold value. ### Claim 14 (depends on 11) The image forming apparatus according to claim 11, further comprising: a processor configured to control the conveyance speed according to the command issued by the control circuit. ### Claim 15 (depends on 14) The image forming apparatus according to claim 14, wherein the processor is configured to determine a size of the medium, the control circuit is configured to determine whether the size of the medium is smaller than a predetermined size, and the control circuit does not issue the command when the size of the medium is not smaller than the predetermined size. ### Claim 16 (depends on 11) The image forming apparatus according to claim 11, wherein the control circuit determines the estimated temperature of each of the first and second heaters further based on a previously estimated temperature thereof. ### Claim 17 (depends on 11) The image forming apparatus according to claim 11, wherein the control circuit determines the estimated temperature of each of the first and second heaters based on a corresponding equivalent thermal circuit. ### Claim 18 (depends on 17) The image forming apparatus according to claim 17, wherein the equivalent thermal circuit for each of the first and second heaters includes a resistor representing heat dissipation by the medium, and the resistor of the equivalent thermal circuit for the first heater has a resistance value smaller than the resistor of the equivalent thermal circuit for the second heater. ### Claim 19 (depends on 11) The image forming apparatus according to claim 11, wherein the first heater is located at the center of the medium when the medium is conveyed when viewed in the second direction. ### Claim 20 (depends on 11) The image forming apparatus according to claim 11, wherein the fixing device includes a roller in which the heaters are disposed.