Microprocessor-controlled apparatus for detecting and guiding a web wherein right and left eyespots are formed to determine right and left edges

摘要

An apparatus for detecting and guiding a web includes a web scanner bar unit that extends across the entire width of the web path for controlling a steering mechanism to maintain a more precise edge and/or center alignment. The web scanner bar unit is formed of an infrared light-emitting diode array and a phototransistor array formed on opposite sides of the web. A microprocessor-based controller unit is provided for controlling the operation of the web scanner bar unit to form right and left eyespots in order to determine the respective right and left edges of the web. Further, the web scanner bar unit is capable of detecting a break in the intermediate area of the web.