METHOD AND SYSTEM FOR DETECTING THE POSITION OF AN EDGE OF A WEB

摘要

A method and system for determining the lateral position of an edge of a web are disclosed. The system includes a plurality of optical transmitters, a plurality of optical receivers, a plurality of ultrasonic transmitters, a plurality of ultrasonic receivers, and a controller. The controller is used to determine which type of transmitter and receiver should be used in conjunction with the specific web to be processed. The controller activates certain optical transmitters and determines the amount of optical occlusion that results from the web being between the optical transmitters and receivers. The controller also activates certain ultrasonic transmitters and determines the amount of sound occlusion that results from the web passing between the ultrasonic transmitters and receivers. The type of transmitter/receiver that results in the most occlusion can then be selected to determine the position of the edge of the web. Once selected, only one type of transmitter/receiver is preferably used at a given time to determine the position of the edge of the web, and position the web accordingly. A compensation beam can also be used to further enhance the accuracy of the determination of the web's position.