Online sheet width measurement

The problem

Camera systems with backlit illumination are often used to measure sheet width online. However, these systems can only detect a single edge using a shadow principle and are not able to measure the cross sectional profile of each edge. The camera also needs to be positioned high above the sheet and this is not possible where access is limited. Moreover, the camera system is highly sensitive to changes in ambient lighting.

 

The solution

Sigmavision offers and additional module for its calendered sheet thickness system to measure sheet width. Two laser sheet of light sensors are mounted on the line, one to detect each edge of the sheet. By calibrating the position of each sensor the sheet width can be determined. Where sheet of different widths are produced on the same line linear actuators may be employed to index each sensor to a position where the sheet edge lies within the sensor's field of view. Read more