METHOD AND APPARATUS FOR MONITORING A PATTERN OF AN APPLIED LIQUID

摘要

A method for monitoring the quality of a pattern of fluid beads (50) applied to a moving substrate (40) measures time delays between the passage of reference points on a substrate element and leading (51) and trailing (52) edges of a bead (50), the quality of which is to be measured. Time delay ratios are generated, and compared to reference ratios. The result of the comparison is indicative of variations in the quality of the measured bead. The invention has utility in a variety of industries, including industries in which adhesive beads are applied to a substrate, such as the envelope and box industries. An apparatus in accordance with the invention may conveniently utilize non-contact sensors (9) to monitor the passage of the substrate (40) and beads (50), and further may advantageously monitor the leading (41) and trailing (42) edges of the substrate and leading (51) and trailing (52) edges of the beads (50).