Monitor to determine the formation and/or formation index of a running paper or cardboard web has a LED array to illuminate the web and matrix camera(s) linked to a common server through a frame grab card or computer

摘要

To determine the formation and/or formation index of a running web (12), especially of paper or cardboard, it is illuminated by at least one light emitting diode (LED) array (16). At least one camera (14) is used to register the light at the web, connected to a computer (20). Several matrix cameras (14) are used, linked to a common server (22) through a frame grab card and/or an evaluation computer (20), or connected to a computer which simultaneously is an evaluation and server unit. The matrix camera (14) is a charge coupled device (CCD) camera and pref. a monochrome CCD camera. The lateral formation profile is established over the whole web width, by the matrix cameras (14) across it. The measured values give the control parameters for the prodn. process, through a quality control system (QCS). The separate photographed image points have a surface which does not exceed 1 mm2. The light illumination is at least partially through the web (12) or at least partially reflected from the web when wet. The measurements are taken directly after the water line on the fourdrinier, and the images are recorded in synchronization with the flash intervals of the LED arrays (16). The illumination is from an infra-red LED array (16), and at least one matrix camera (14) is fitted with a filter. The images taken by the camera(s) (14) are initially processed by the connected evaluation computer (20), to give a corrected gray stage image for the formation analysis. The different gray stages are registered numerically to give the formation index. At least two cameras (14) are used to show the fiber orientation, aligned at a web zone. Both cameras (14) are pref. fitted with polarizing filters on different polarization planes, with an automatic interchange between their use. One camera can be used, fitted with a rotating polarizing filter, and an additional filter which is sensitive to changing wavelengths. The flocking orientation is derived from the image data which pref. give an indication of the fiber orientation. Together with the image evaluation with filters, at the same time other measurements are made of the web material weight, residual moisture content, thickness, and the like, from characteristics which can be registered optically. At least one LED array has different colors and pref. flashes alternately with 600 nm, 900 nm and 1400 nm. An Independent claim is included for an appts. (10) to monitor a running web (12), with pref. a number of matrix cameras (14), each connected to a common server (22) through a frame grab card and/or an evaluation computer (20).