Detecting transparent foil labels on transparent bearer foil involves passing polarized light through foil and polariser and assessing detected intensity change as indicating presence of label

摘要

The method involves moving the foil (2) with labels (4) relative to a light beam (39) with polarized light so that the foil and labels are alternately through illuminated by the light, light passing though the foil or the foil and label is then passed through a polariser and the intensity of the light passed through the polariser is measured and an intensity change assessed as indicating the presence of a label. Independent claims are also included for the following: an arrangement for detecting transparent foil labels on a transparent bearer foil.