Foreign fiber i.e. thread, detecting method for use in longitudinal moving fiber stand, involves forming ratio from absolute deviation and predetermined fixed value that is specified for fiber stand

摘要

The method involves emitting light in direction of a fiber stand (1), and determining brightness value of thread from the light reflected in the thread. The brightness value is continuously checked to deviation from luminance average value. Ratio is formed from absolute deviation and predetermined fixed value that is specified for the fiber stand, and is utilized for evaluation of the deviation. The fixed value is changed when changing the thread color, where the fixed value and predetermined value does not go below the specified value. An independent claim is also included for a device for optically detecting foreign fiber i.e. thread, in a longitudinal moving fiber stand, comprising a light source.