METHOD AND APPARATUS FOR DETECTING THE PRESENCE OF FLAWS IN A MOVING SHEET OF MATERIAL

摘要

The present disclosure describes an apparatus and a method for detecting the presence of flaws in a moving sheet of material. The apparatus comprises a light source for projecting a light beam; a beam shaping unit for shaping the light beam into a predetermined structured light pattern, and projecting the structured light pattern onto a portion of the surface of the sheet; an optical unit for collecting light emitted from the portion of the surface; and a light detecting unit for receiving the light collected by the optical unit and generating an electrical signal indicative of the intensity of the light generated from the portion of the surface. A signal processing unit is provided for filtering the electrical signal, the signal processing unit having predetermined characteristics specifically adapted to match an expected electrical signal corresponding to the predetermined structured light pattern. The present invention can be used in a transmission mode wherein the light beam is projected onto one side of the moving sheet and detected from the opposite side, or in a reflective mode wherein the light beam is projected onto and detected from the same side of the moving sheet.