Development of On-line System for Measuring Fiber Orientation on Paper Surface

Abstract:

An on-line sensor system for measuring fiber orientation of paper was newly developed. The sensor has a special optical configuration to measure light reflected from the surface of paper running at high speed. The sensor is composed of unpolarized light source that illuminates paper surface perpendicularly, several photo detectors and polarizers attached to the detectors. The detectors are distributed on the circumference of a circle defined in a plane being parallel with the paper surface.

The intensity of the light reflected from paper surface is measured substantially in the same instant by the detectors. Fiber orientation is determined by the angular dependence of the light intensity. The anisotropy is a direct result of the light reflection from the lateral surfaces of the fibers.

Two sensors, which were prepared for measuring both felt and wire sides of paper, were installed between the calender roll and the reel of a paper machine in Komatsushima Mill. We succeeded in measuring fiber orientation profiles in the cross machine direction and the machine direction. These sensors had been used to control quality for curling of copy paper in the mill for five years.

The technology was licensed to Yokogawa Electric Corporation. Two pairs of sensors, which were incorporated into the B/M7000XL, have been used in the mill since July 1997. Three pairs of manufactured goods have been applied in two of our mills up to now.