Patent ID: 11914316
Assignee: CANON KABUSHIKI KAISHA
Field: Optics (Instruments)
Classification: CPC G  H | IPC G  H

Claim 7:
8. An image forming apparatus comprising:
an image forming unit configured to form an image on a sheet;
a fixing unit configured to fix the image to the sheet, the fixing unit including:
a first heater to which a first current is supplied from a first commercial power source to generate heat, the first heater including a first region capable of heating and a second region capable of heating, the first region and the second region being located at different positions in a lengthwise direction, and a heat generation capacity in the first region being higher than a heat generation capacity in the second region;
a first switch provided in a current line between the first commercial power source and the first heater and configured to switch whether or not to supply the first current to the first heater;
a second heater to which a second current is supplied from a second commercial power source different from the first commercial power source to generate heat, a heat generation distribution characteristic in a lengthwise direction of the second heater being different from a heat generation distribution characteristic in a lengthwise direction of the first heater, the second heater including a third region capable of heating and a fourth region capable of heating, the third region and the fourth region being located at different positions in a lengthwise direction, a heat generation capacity in the third region of the second heater in the lengthwise direction being lower than a heat generation capacity in the fourth region, different from the third region, of the second heater in the lengthwise direction;
wherein in the lengthwise direction of the first heater, the first region of the first heater and the third region of the second heater overlap, and
in the lengthwise direction of the first heater, the second region of the first heater and the fourth region of the second heater overlap; and
a second switch provided in a current line between the second commercial power source and the second heater and configured to switch whether or not to supply the second current to the second heater; and

a controller configured to:
in an image forming mode in which the image is formed on the sheet, control the first switch and the second switch to keep a temperature of the fixing unit at a fixing temperature serving as a target temperature for fixing the image on the sheet; and
in a standby mode in which the image is not formed on the sheet, control the first switch and the second switch to keep the temperature of the fixing unit at a standby temperature as a target temperature in the standby mode, and control the first switch and the second switch such that a timing at which the first current starts being supplied from the first commercial power source and a timing at which the second current starts being supplied from the second commercial power source are different in order to make a speed at which the temperature of the fixing unit rises lower than in a case where the timing at which the first current starts being supplied from the first commercial power source and the timing at which the second current starts being supplied from the second commercial power source are the same.