Zero tension web unwinder apparatus and method

Apparatus for the substantially tensionless unwinding of a web of cigarette filter material wound on a bobbin comprising:

• means supporting the bobbin for rotation;
• a servomotor for rotating the bobbin in a direction to unwind the web therefrom;
• a cigarette filter maker located downstream of the bobbin supporting means for taking up said web and forming a cigarette filter from said web, said maker having a web take-up speed;
• an encoder on said maker for generating a first output signal corresponding to the web take-up speed of the maker, said web passing along a path of travel from said bobbin to said maker and forming a web loop therebetween;
• a sensor disposed in spaced, non-contacting relation to the web loop along the path of travel of the web for sensing the position of the web loop, said sensor having a second output signal corresponding to the position of the web loop in relation to the location of the sensor;
• and
• a servo control system responsive to the first and second output signals for producing a control signal based on the first and second output signals and for transmitting the control signal to the servomotor so as to rotate said bobbin at a speed to maintain the web in a substantially tensionless state.

A method for the substantially tensionless unwinding of gossamer web materials wound on a bobbin comprising:

• rotating the bobbin in a direction to unwind the web therefrom;
• taking up said web on a handling apparatus at a take-up speed;
• passing said web along a path of travel from said bobbin to said handling apparatus and forming a web loop therebetween;
• generating a first output signal corresponding to the take-up speed of the handling apparatus;
• sensing the position of the web loop with a sensor disposed in a non-contacting, spaced relation to the web loop along said path of travel;
• generating a second output signal from said sensor corresponding to the position of the web loop;
• controlling, in response to the first and second output signals, the speed of rotation of said bobbin so as to maintain said web in a substantially tensionless state;
• and
• impinging a low pressure air stream on said web loop adjacent the sensor.