Expandable, continuous illumination source for a web inspection assembly and method

An illumination system for use with an optical web inspection assembly to identify surface defects on a moving material web, said illumination system comprising:

• an elongated first light source configured to generate a substantially continuously, non-collimated first elongated strip of light therefrom generally in an exit direction to impinge the material web;
• an elongated intermediate light source having a longitudinal axis offset from a longitudinal axis of the first light source, and adapted to generate a substantially continuous, non-collimated intermediate elongated strip of light therefrom generally in an entrance direction;
• and
• an elongated curved light pipe device positioned adjacent to said intermediate light source and having an elongated entrance end and an opposite elongated exit end, said entrance end being configured to substantially receive the intermediate strip of light of the intermediate light source generated in the entrance direction, said light pipe having a smoothly curved interior wall portion between the entrance end and the exit end configured to reflect and transmit substantially all said intermediate strip of light collected in said entrance end for transmission through said exit end generally in the exit direction, and in substantially an end-to-end aligned manner where a proximal end of a reflected intermediate strip of light is substantially linearly aligned with a distal end of the first strip of light such that the first strip of light and the reflected intermediate strip of light collectively form a substantially linear, continuous and uniformly distributed line of illumination on a surface of the material web.

The illumination system as defined in claim 32 wherein,

• said regulating device includes:
• a first ballast device operatively coupled to the first light source for independent incremental adjustment of the power to the first light source;
• and
• an intermediate ballast device operatively coupled to the intermediate light source for independent incremental adjustment of the power to the intermediate light source.

A method of illuminating a moving material web for use with an optical web inspection assembly to identify surface defects comprising the steps of:

• emitting a substantially continuous elongated strip of light from a light source in an entrance direction;
• receiving said strip of light in an elongated entrance end of an elongated light pipe;
• reflecting said strip of light, traveling in the entrance direction, in said light pipe off of smoothly curved interior wall portion between the entrance end and an elongated exit end and defining an optical path configured to reflect and transmit substantially all the light received from said entrance end to said exit end for exit therefrom in a line of illumination generally in an exit direction toward the moving material web such that the intensity of said line of illumination exiting the exit end is substantially equal to the intensity of said strip of light entering the entrance end from said light source;
• and
• illuminating the moving web with the line of illumination transmitted from said exit end of the light pipe.