Tension control apparatus for thermal vaporizing coating device

Claim 1

A TENSION CONTROL APPARATUS FOR A WEB INCLUDING A VACUUM CHAMBER, WHICH COMPRISES A SHAFT HOLDING A SUPPLY ROLL OF THE WEB AGAINST ROTATION RELATIVE THERETO, BEARINGS MOUNTED ON THE WALLS OF THE CHAMBER SUPPORTING THE SHAFT ROTATABLY, AN ELECTROCONDUCTIVE DISC KEYED TO THE SHAFT, AN ELECTROMAGNET PROVIDED WITH A COIL AND POLE PIECES SO SPACED AS TO CLOSELY BRACKET THE DISC, A SUPPORT MOUNTED ON A WALL OF THE CHAMBER FOR MOUNTING THE ELECTROMAGNET IN A POSITION IN WHICH THE POLE PIECES BRACKET THE DISC, A VARIABLE RESISTANCE INCLUDING A RESISTOR AND A CONTACTOR MOUNTED IN THE CHAMBER, A GUIDE MOUNTED IN THE CHAMBER, A PINION MOUNTED ON THE GUIDE AND FIXED TO THE CONTACTOR, A RACK MESHING WITH THE PINION AND SLIDABLE IN THE GUIDE, A PIVOTALLY MOUNTED FEELER URGED INTO ENGAGEMENT WITH THE ROLL, A LINK CONNECTING THE RACK TO THE FEELER, AND MEANS FOR SUPPLYING POWER TO THE ELECTROMAGNET THROUGH THE VARIABLE RESISTANCE.