US 12,124,196 B2
Image forming apparatus and image fixing method
Yohei Doi, Mishima Shizuoka (JP)
Assigned to Toshiba Tec Kabushiki Kaisha, Tokyo (JP)
Filed by Toshiba Tec Kabushiki Kaisha, Tokyo (JP)
Filed on Oct. 4, 2023, as Appl. No. 18/480,874.
Application 18/480,874 is a continuation of application No. 17/463,462, filed on Aug. 31, 2021, granted, now 11,809,108.
Application 17/463,462 is a continuation of application No. 17/003,880, filed on Aug. 26, 2020, granted, now 11,150,582, issued on Oct. 19, 2021.
Claims priority of application No. 2019-228869 (JP), filed on Dec. 19, 2019.
Prior Publication US 2024/0045358 A1, Feb. 8, 2024
Int. Cl. G03G 15/20 (2006.01)
CPC G03G 15/205 (2013.01) [G03G 15/2053 (2013.01); G03G 2215/00734 (2013.01)] 16 Claims
OG exemplary drawing
 
1. An image forming apparatus, comprising:
a fixing device configured to fix an image to a sheet and including a first heating source and a second heating source, the second heating source having a heating width greater than a heating width of the first heating source; and
a controller to select one of the first heating source or the second heating source in accordance with a size of a sheet to be supplied to the fixing device for fixing, wherein
if one of the first heating source and the second heating source fails, the controller is configured to select the other one of the first heating source and the second heating source irrespective of the size of the sheet,
the first heating source and the second heating source are spaced from each other in a conveyance direction of the sheet through the fixing device,
the first heating source has a resistance temperature coefficient (TCR) characteristic such that a change in output power will be less than a threshold value in accordance with a change in temperature,
the second heating source has a resistance temperature coefficient (TCR) characteristic that a change in output power is equal to or greater than the threshold value in accordance with a change in temperature,
the second heating source has a heating output power that decreases with increases in temperature, and
the first heating source has a heating output power that decreases with increases in temperature less than the second heating source.