Optical web inspection system

摘要

The specification discloses an optical web inspection system for detecting imperfections in a web having a longitudinal axis and moving in a plane across an inspection area. Radiation means is disposed above the plane of the web and transverse to the longitudinal axis of the web for directing radiant energy on the web at the inspection area. A plurality of sensors are mounted transverse to the longitudinal axis of the web and above the inspection area for receiving reflected radiation from successive transverse portions of the web passing across the inspection area. The plurality of sensors generate electrical output signals representing the intensity of the reflected radiation from the successive transverse portions of the web. Circuitry for periodically summing the electrical output signals from selected ones of the sensors is provided to generate a summation signal representative of the sum of reflected radiation from selected discrete segments of a plurality of the transverse portions of the web. The system further includes circuitry for comparing at least one of the electrical output signals with the summation signal for determining whether an imperfection exists within the web.