METHOD OF INSPECTING A WEB OF TRANSLUCENT MATERIAL, ESPECIALLY PHOTOGRAPHIC PAPER

摘要

A method of visually inspecting the formation of a web of translucent material by means of a device it moves past. The device consists of a source of light on one side of the web generating a beam of light of a desired hue and intensity that penetrates the web, and a video camera on the side of the web away from the source of light, intercepting the beam and converting it into a video signal that is forwarded to a monitor. The source of light emits the beam in a flash of duration t1 that is too short for the web to advance far enough while illuminated to blur the image. The image on the monitor is accompanied by a reference image.