| 摘要 |
A device for determining and adjusting the position of a web, the device having two sensor units each with a respective light source element directed towards the web and a respective photoelectric sensor element responsive to reflected light, a control unit responsive to respective output signals of the two sensor units, and a device connected to the control unit and fed by an adjusting signal from the control unit for adjusting the position of the web, including reflectors disposed at a side of the web facing away from the sensor units and projecting beyond respective opposite edges of the web, one of the two elements of one of the sensor units being directed towards one of the opposite edges of the web and the other of the two elements of the one of the sensor units being directed to a reference surface, the other of the two elements of the other sensor unit being directed towards the other of the opposite edges of the web and the other of the two elements of the other sensor unit being also directed to a reference surface, the adjusting signal fed from the control unit to the adjusting device being a function of the difference of the two output signals of the two sensor units. |
