1. Field of the Invention
The present invention relates to a solid-state sensor system for determining the position of at least one edge of a web material.
2. Prior Art
Web edge sensor systems having a transmitter disposed on one side of a web and a receiver disposed on the other side of the web for locating the position of an edge of the web therebetween, are known in the art. To determine information such as the web center, the prior art web edge sensor systems require two sensors. Under this scheme, the two sensors are located at the lateral web edges and are positioned perpendicular to the web direction of travel. The sensors are mounted on mechanical drive systems which adjust the position of the sensors via belts and motors in response to periodic lateral web travel.
The drive system of the prior art web edge sensor systems maintains the position of the sensor relative to the web, which is disposed in between the sensor transmitter and receiver, to accurately determine web location and travel. However, such drive systems are complex and have many moving parts. These drive systems suffer from mechanical error, operate incorrectly, or in some cases completely fail as a result of their complexity. Even minor mechanical error can result in stoppage of the web production line to replace or repair the drive systems. Such interruptions are inefficient and costly.
Thus, a need exists for a sensor system which does not suffer from the aforementioned problems caused by sensors requiring complex mechanical drive systems, as described above, while continuing to accurately determine the web location and movement. It is to such an improved sensor system that the present invention is directed.