Method and device for influencing the fan-out effect
A device is used to influence the fan-on effect of a web in a web-fed rotary printing press. Sensors are used to sense and to monitor a side register control or adjustment of the web. The values provided by the sensor are supplied to the device which controls the fan-out effect.
1. A method for affecting a fan-out effect on a printed image on a web including:
providing a web having a web width;
providing an image on said web;
providing first and second image points of two image portions of a color separation of a defined color of said printed image;
locating said first printed image point at a first location with respect to said web width and locating said second printed image point at a second location with respect to said web width, said first and second locations being spaced from each other laterally on said web width;
providing a sensor;
using said sensor for determining said first and second locations of said first and second printed image points of said two printed image portions of said color separation of said printed image;
providing reference image data of said first and second image points of said two printed image portions of said color separation of said defined color of said printed image from a print pre-stage;
using said print pre-stage image data for determining reference locations of said first and second image points;
comparing locations of said printed images of said first and second image points, in respect to their axial positions on said web with said reference locations of said first and second image points;
determining lateral deviations of said first and second image points of said printed image from said reference locations of said first and second image points resulting from at least one of an increase in said web width caused by said fan-out effect of said web and a registration error occurring during said printing of said image on said web;
extrapolating said lateral deviations of said first and second image points of said printed image for a plurality of image points of said printed image portions of a color separation of said defined color of said printed image;
providing an actuating member for affecting said fan-out effect;
sending an actuating command to said actuating member when said lateral deviations of said printed image points exceeds a preset nominal value; and
using said actuating member for affecting said fan-out of said web.
2. The method of claim 1 further including providing a scanning width including a center of said web and determining said lateral registration error of said image area from its nominal position with respect to said center of said web.
3. The method of claim 1 further including using said sensor for detecting said image points of said printed image over at least one half of said web width.
4. The method of claim 3 further including using said sensor for detecting said image points of said printed image over a whole width of said web.
5. The method of claim 1 further including providing said sensor as a line camera.
6. The method of claim 1 further including providing said sensor as a planar sensor.