Image forming apparatus and image forming method for controlling a primary heating and a secondary heating of a fixing device

摘要

An image forming apparatus includes a controller including a primary heating control portion that determines a first amount of power supplied to a heater based on a temperature of a fixing rotator detected by a temperature detector and controls the heater to perform a primary heating to heat the fixing rotator with the first amount of power, a secondary heating control portion that controls the heater to perform a secondary heating to heat the fixing rotator with a preset second amount of power, and a switch portion that controls the heater to switch between the primary heating and the secondary heating during an identical print job without changing a target temperature of the fixing rotator.

主权项

1. An image forming apparatus comprising:
a fixing rotator rotatable in a predetermined direction of rotation; a heater disposed opposite the fixing rotator to heat the fixing rotator; an opposed rotator to press against the fixing rotator to form a fixing nip therebetween through which a recording medium bearing a toner image is conveyed; a temperature detector disposed opposite the fixing rotator to detect a temperature of the fixing rotator; and a controller operatively connected to the temperature detector and the heater, the controller including: a primary heating control portion to determine a first amount of power supplied to the heater based on the temperature of the fixing rotator detected by the temperature detector and to control the heater to perform a primary heating to heat the fixing rotator with the first amount of power; a secondary heating control portion to control the heater to perform a secondary heating to heat the fixing rotator with a preset second amount of power; a switch portion to control the heater to switch between the primary heating and the secondary heating during an identical print job without changing a target temperature of the fixing rotator; and a correction portion, operatively connected to the temperature detector and the secondary heating control portion, to change the preset second amount of power supplied to the heater in the secondary heating by adding or subtracting a correction amount of power to the preset second amount of power, and the correction portion multiplies the correction amount of power by a correction coefficient when an interval between plural recording media changes.