Patent ID: 11874619
Assignee: BROTHER KOGYO KABUSHIKI KAISHA
Field: Optics (Instruments)
Classification: CPC G | IPC G

Claim 13:
14. A control method for an image forming apparatus, the image forming apparatus comprising:
a toner image forming unit configured to form a toner image on a sheet,
a fuser comprising a heater and configured to fix the toner image onto the sheet; and
a controller configured to exercise a standby control under which a temperature of the fuser is maintained within desired limits at temperatures around a target standby temperature, the standby control comprising:
repeating a control cycle that includes:
energizing the heater with an energization amount En during a preset heating period in a case where the temperature of the fuser has dropped to a temperature below the target standby temperature; and
waiting until the temperature of the fuser drops to the target standby temperature in a case where the temperature of the fuser has risen to a temperature equal to or above the target standby temperature after the preset heating period has elapsed;

measuring a temperature fluctuation period that is a time period from start of energizing the heater to an end of the control cycle; and
setting an energization amount En+1 for a next control cycle, based on the measured temperature fluctuation period, wherein:
in a case where the temperature fluctuation period of a last control cycle is shorter than a first threshold, the energization amount En+1 for the next control cycle is set at an amount greater than an energization amount En for the last control cycle,
in a case where the temperature fluctuation period of the last control cycle is equal to or longer than a second threshold greater than the first threshold, the energization amount En+1 for the next control cycle is set at an amount smaller than the energization amount En for the last control cycle; and
in a case where the temperature fluctuation period of the last control cycle is equal to or longer than the first threshold and shorter than the second threshold, the energization amount En+1 for the next control cycle is set at a same amount as the energization amount En for the last control cycle.