Patent ID: 6849851

Claim:
A method in the process of manufacturing and/or finishing a fibre web, in which method said continuous and moving web, is monitored in a time-resolved manner and in synchronization with the movement of the web by one or more thermal cameras of the infrared range or with a corresponding detector/detectors for the purpose of controlling the quality or condition, said method comprising the steps: in the direction of the movement of the web, a continuous two-dimensional thermal image, i.e. a continuous thermal chart of the web is formed by said detector/detectors for analyzing the formed continuous thermal chart, the continuous thermal chart is divided into successive matched partial charts where the cycle length used in forming the partial charts is selected to correspond to the length of influence specific to the means related to the processing of the passing web and for detecting the malfunctioning of the means related to the processing of the web on the basis of a periodical marking caused by said means in the passing web, local deviations and/or discontinuities particularly in the direction of movement of the web in the temperature are detected from the said matched partial charts.