Printing system having optical supervision apparatus of a substrate running web, particulary a paper web

In combination with a printing machine system (18, 21, 22, 19, 20), having a damaged web damage control unit (10),

• apparatus (2, 23) for optical supervision of the web (1) running through the printing machine system, and for generating a defect signal upon sensing a deviation of the web from a normal condition,
• said apparatus comprising
• an elongated light source (12) positioned transversely to the longitudinal extent of the web (1) at one side thereof, and being wider than the width of the web to be supervised;
• an optical scanner (3) including a plurality of fiber optic light guides (4) positioned at the other side of the web,
• whereby the web will pass between said light source and said scanner,
• said plurality of light guides being located in a line across the web and positioned to receive light from the elongated light source to form a linear line scanner (5), said linear line scanner being wider than the width of the web to be supervised;
• a charge coupled device (CCD) sensor chip (7) having individual pixels directly coupled to the light guides (4) and receiving optical signals directly from said light guides, said charge coupled device sensor chip (7) transducing said optical signals into electrical signals from each of the light guides;
• a light guide bundling element (6) for bundling the light guides (4) together to have a linear extent substantially smaller than the width of the web, and unambiguously associating each of the light guides (4) and hence the light from any one of the light guides with a specific pixel of the charge coupled device sensor chip (7),
• wherein at least one light guide is positioned on both sides of the web to be supervised beyond the width of the web, and said elongated light source (12) extends to a region beyond the sides of the web to illuminate, under normal conditions at all times, the light guides located beyond the sides of the web to be supervised;
• a signal evaluation and control unit (9) coupled to the charge coupled device sensor chip (7) and providing defect signals if the signals from the charge coupled device sensor chip (7) deviate from a standard signal representative of normal condition;
• and
• coupling means (15) connecting said signal evaluation and control unit (9) to said damage control unit (10).