Image forming apparatus

摘要

Heat-equalizing rotation of a fixing member and a pressing member for equalizing the distribution of the temperature of a surface of the fixing member in a width direction is performed after a recording medium having a size less than or equal to a predetermined size in the width direction passes a nip portion and before a recording medium having a size greater than the predetermined size in the width direction passes the nip portion. Further, a termination condition of the heat-equalizing rotation is selected from among a plurality of different kinds of termination conditions, based on image formation related information related to next image formation performed after the heat-equalizing rotation.

主权项

1. An image forming apparatus including a fixing device, the fixing device comprising:
a rotatable fixing member having an endlessly moving surface; a heat source that heats the fixing member; a rotatable pressing member that is pressed and comes in pressure-contact with the fixing member so as to form a nip portion therebetween; a rotary drive unit that rotationally drives the fixing member or the pressing member; a control unit configured to control the rotary drive unit to perform heat-equalizing rotation of the fixing member and the pressing member for equalizing distribution of temperature of the surface of the fixing member in a width direction orthogonal to a recording medium conveying direction at the nip portion, at a time after a recording medium having a size less than or equal to a predetermined size in the width direction passes the nip portion and before a recording medium having a size greater than the predetermined size in the width direction passes the nip portion, wherein
the control unit is configured to select a termination condition of the heat-equalizing rotation from among a plurality of different kinds of termination conditions based on image formation related information related to next image formation to be performed after a next heat-equalizing rotation; anda temperature detecting unit that detects temperature of at least one of members constituting the fixing device, the temperature detecting unit being disposed at a position facing an end in the width direction of the fixing member, whereinthe termination conditions include a condition that a detection result of the temperature detecting unit corresponds to a predetermined temperature set in advance, wherein the image formation related information related to the next image formation performed after the heat-equalizing rotation is image information of an image to be formed after the heat-equalizing rotation,the image formation of the image indicates that a job is either a color image or a monochromatic image, andthe predetermined temperature for the termination conditions of the heat-equalizing rotation is set differently between when the job is the color image and when the job is the monochromatic image, the predetermined temperature being set higher for the monochromatic image than for the color image.