Evaluation of tribological properties of pick up roller measured using a laser microscope with a wide field of view

Analysis of contact conditions between rubber rollers and printing paper is important for stable paper feeding operation. Direct observation of apparent contact area is necessary to understand contact conditions, such as distributions of real contact area and micro-slips. However, conventional optical microscopy takes too long to observe the whole apparent contact area because the field-of-view is too narrow. We developed a wide field-of-view laser microscope, and applied it to determine the distributions of real contact area of rubber rollers against glass plates. Critical torques at which micro-slips of the rubber rollers occurred were proportional to total real contact area.