Web tension control

Claim 1

IN APPARATUS FOR THE CHARACTER DESCRIBED FOR OPERATING ON WEB MATERIAL, THE COMBINATION OF MEANS FOR SUPPORTIONG A SUPPLY ROLL OF THE WEB MATERIAL INCLUDING A ROTATABLY MOUNTED SHAFT AND AN ADJUSTABLE BRAKE CONNECTED TO CONTROL ROTATION OF SAID SHAFT, MEANS SUCH AS A PRINTING COUPLED MOUNTED IN SPACED RELATION TO SAID SHAFT AND ADAPTED TO PERFORM AN OPERATION ON THE WEB MATERIAL, MEANS FOR FEEDING THE WEB MATERIAL FROM A ROLL MOUNTED ON SAID SHAFT TO SAID MEANS FOR OPERATING ON THE MATERIAL INCLUDING AN UNWIND DRUM ARRANGED TO RECEIVE THE WEB AGAINST ITS SURFACE AND TO PROVIDE A FRICTION UNWIND DRIVE FOR THE WEB MATERIAL, A MOTOR DRIVE CONNECTED TO ROTATE SAID DRUM AND TO DRIVE SAID MEANS OPERATING ON THE WEB MATERIAL AT A CORRELATED SPEED, IDLER MEANS MOVABLY MOUNTED TO CONTACT THE WEB MATERIAL BETWEEN THE SUPPLY ROLL AND SAID UNWIND DRUM AND TO FOLLOW THE WEB MATERIAL IN RESPONSE TO CHANGES IN TENSION THEREOF, A CONTROLLER FOR SAID BRAKE INCLUDING A VARIABLE CONTROL MEANS RESPONSE TO MOVEMENT OF SAID IDLER MEANS TO ADJUST THE RETARDING FORCE APPLIED BY SAID BRAKE TO MAINTAIN A DESRIDE TENSION DURING UNWINDING OF THE WEB MATERIAL A DESIRED TENSION ROLL, AND A CONTROL CIRCUIT CONNECTED TO SAID CONTROLLER TO MODIFY THE OPERATION THEREOF BY APPLYING A SUBSTANTIALLY GREATER RETARDING FORCE WITH SAID BRAKE TO THE SUPPLY ROLL WHEN THE DRIVING POWER TO SAID UNWIND DRUM IS STOPPED.