Web cutting position control system

Claim 1

A web cutting position control system comprising: cutting means for cutting a web that is running continuously including a rotating cutting cylinder arrangement; phase detecting means associated with said cutting means for outputting pulses corresponding to the rotational angle of the cutting cylinder arrangement; a compensating roller operatively engaged with the web and movable between a first position and a second position for changing the path length of the web relative to said cutting means; movement detecting means for detecting the movement and position of said compensating roller; synchronizing mark detecting means, installed downstream of said compensating roller for detecting each of a plurality of synchronizing marks provided on said web; counting means connected to said synchronizing mark detecting means and connected to said phase detecting means for counting the pulse output of said phase detecting means until said synchronizing mark detecting means detects one of said synchronizing marks on said web and outputting a signal representing the number of pulses counted; reference value memory means for storing in advance a reference value representing a number of pulses output by said phase detecting mean up to the sensing of one of said plurality of synchronizing marks for a predetermined preferred positional relationship between said cutting means and the web; comparing means for receiving said reference value and said count signal from said counting means and outputting a signal representing the value of the difference between said reference value signal and said count signal; and, controlling means for receiving said difference signal and for controlling the direction and amount of movement of said compensating roller dependent upon the value of said difference signal.