IMAGE-FORMING APPARATUS

摘要

An image-forming apparatus is provided in which power is supplied to a heater at the smaller duty ratio of an upper-limit duty ratio D15a which is set according to the current detected by an inlet current detecting unit in a warm-up period of a fixing unit and a duty ratio Dn which is continuously corrected according to a change in a heater resistance value and is required for supplying a predetermined target power to the heater. The image-forming apparatus can output a first page of recording material in a short period time so that a current consumption of the entire apparatus does not exceed rated current consumption.

主权项

1. An image-forming apparatus comprising:
an image forming unit that forms a toner image on a recording material; a fixing unit that has a heater, the resistance value of which changes with an increase in temperature, and heats and fixes the toner image formed on the recording material to the recording material; a control unit that controls the apparatus; an inlet current detecting unit that detects current flowing into the entire apparatus; and a heater current detecting unit that detects current flowing into the heater, wherein when warming up the fixing unit to a fixable temperature, the control unit supplies power to the heater with the smaller duty ratio of: an upper-limit duty ratio D15a of power supplied to the heater, the ratio being determined so that the current detected by the inlet current detecting unit does not exceed a predetermined current; and a duty ratio Dn which is determined based on the resistance value of the heater corresponding to the temperature of the heater and the current detected by the heater current detecting unit and which is continuously corrected according to a change in the resistance value and is required for supplying predetermined target power.