Measurement/control of sheet material using at least one sensor array.

摘要

A paper web (102) is monitored for measurement and manufacturing control by a stationary web sensor (132) extending across the entire web which is raster scanned by the motion of the web (102). Massive amounts of data are processed by a look up table memory addressed by digitized sensor data and the output from a reference memory containing element specific information. The lookup table is loaded with data to define a characteristic or property of the web corresponding (102) to digitized sensor data interpreted in view of element specific data from the reference memory. Rapidly processed data is stored in a memory in a form facilitating its display and interpretation by an operator of the web manufacturing machine (100) and also control of the machine. By controlling operation of the machine, uniformity of the web is substantially improved and, by taking the measurements closely adjacent the initial processing end of the web, corrections of nonuniformity in the web are quickly effected. To measure and control absolute characteristics and properties of the web, a second, preferably stationary, sensor (210) adjacent the finished end of the web (102) monitors the web adjacent a takeup reel (124). Alternately, for basis weight measurement and control, the weight of the takeup reel (124) is monitored and combined with the web width and machine operating speed to determine an absolute web basis weight. Thus, uniformity of the web and absolute values of characteristics and properties of the web can be measured and controlled.