US 5,512,993 A · Image heating device capable of controlling activation of plural heaters

Abstract

Disclosed is an image heating device for a fixing device in image forming apparatus. The image heating device is provided with two heaters and an image fixing roller. The image fixing roller is heated by the two heaters, one having the heat distribution in the center and the other having the heat distribution in the end portion of the fixing roller. The heaters are alternately energized so that the power requirement is maintained limited. The energization time ratio of the heaters is suitably varied according to the sheet size in order to compensate the temperature loss in the end portions when the heating is conducted in the central portion only, or to reduce the temperature rise in the end portions, encountered when narrow sheets are consecutively passed, thereby preventing various drawbacks resulting from uneven temperature distribution on the fixing roller.

Claims16

Dependent claims

An image heating device comprising:

a heating member including a first heater and a second heater of a heat distribution different from that of said first heater;
a back-up member forming a nip with said heating member;
and
power supply control means for time-shared controlling of electric power supply to said first and second heaters, wherein said power supply control means is adapted to control a time-shared ratio of energization time of said first heater to said second heater in accordance with a number of image heating operations.

1 more element

Dependencies are inferred from the claim text.

Image heating device capable of controlling activation of plural heaters

Life of this patent

Image heating device capable of controlling activation of plural heaters

Life of this patent

Abstract

Claims16