Patent ID: 6744498
Filing Date: 2004-06-01
Classification: B65H,D01H,G01N

Abstract:
A method for optical detection of foreign fibers and other impurities in a longitudinally traveling yarn, comprising the steps of:emitting a light in the direction of the yarn; measuring the intensity of the emitted light; producing a first electrical signal based on the measuring of the emitted light intensity, the first signal being of a value which is a function of the instantaneous diameter of the yarn; following the formation of the first electrical signal, adjusting the intensity of the emitted light as a function of the yarn diameter based on the first electrical signal to compensate for the effect of the yarn diameter on the light reflected by the yarn; then measuring light reflected by the yarn; producing a second electrical signal based on the measuring of the reflected light; and directly using the second electrical signal for detecting impurities in the yarn.