Image forming apparatus including a cleaning sheet for cleaning a peripheral surface of a heat roller

A fixing device comprising:

• a heat roller for heating a toner image formed on an image recording medium to fix the toner image thereto;
• a press roller for pressing said image recording medium against said heat roller;
• a cleaning mechanism including a sheet supply shaft carrying thereon a roll of cleaning sheet in the form of a web, and a sheet winding shaft for winding thereon said cleaning sheet, said cleaning sheet being pressed against said heat roller for cleaning the peripheral surface thereof while being wound on said sheet winding shaft;
• a speed detector for optically detecting an actual speed of movement of said cleaning sheet being wound on said sheet winding shaft;
• and
• a speed control device for controlling a speed of winding of said cleaning sheet based on the detected actual speed of movement of said cleaning sheet detected by said speed detector.

An image forming apparatus comprising:

• a fixing device including a heat roller and a press roller through which an image recording medium carrying thereon a toner image is passed for fixing said toner image to the image recording medium, said fixing device further including a sheet supply shaft carrying thereon a roll of cleaning sheet in the form of a web, a sheet winding shaft for winding thereon said cleaning sheet, and a motor for controllably driving said sheet winding shaft, said cleaning sheet being pressed against said heat roller for cleaning the peripheral surface thereof while being wound on said sheet winding shaft;
• said cleaning sheet being provided on one surface thereof with a pattern of markings;
• an optical sensor for optically detecting said pattern of markings on said cleaning sheet while said cleaning sheet is being moved to be wound on said sheet winding shaft, said optical sensor generating a detection signal when detecting each marking;
• and
• means for calculating an actual speed of movement of said cleaning sheet based on said detection signals from said optical sensor and for controlling a speed of rotation of said motor so that the calculated actual speed of movement of said cleaning sheet approaches a predetermined speed of movement.