A New Photoelectric Device for the Measurement of Yarn Diameter and Yarn Evenness. Part II: The Measurement of Yarn Diameter and the Effect of Shape-error Factor (SEF) on the Measurement of Yarn Evenness

The objective of this paper is to introduce a new method for yarn-diameter and yarn-evenness measurement. The relationship between the diameter of a yarn with a circular cross-section and the output voltage of a sensor device is first derived. The yarn cross-section is then analyzed and the ellipticity of its best-fit ellipse calculated according to the actual yarn cross-section. A sensor device with two incident beams of light perpendicular to each other is described. It was adopted for yarn-diameter measurement with an elliptical cross-section. Finally, a shape-error factor (SEF) in terms of the yarn cross-section is defined in order to improve the measurement of yarn evenness. The results show that the cross-sections of ring-spun and open-end-spun (O.E.) yarns are near to an ellipse and have an irregular outline. The ellipticities of the best-fit ellipses for ring-spun and O.E. yarn are 1.09 and 1.07, respectively. If a sensor device possesses one incident light beam, the measurement errors of yarn dia...