Digital cut-off control

摘要

An improved cut-off control for operating a cut-off mechanism to cut sheets of uniform length from a moving web. The cut-off control comprises means for computing actual sheet length and sheet length error and for generating separate signals indicative thereof. Digital means cylically increment and decrement the actual sheet length signal. Digital means determine whether the sheet length error is within prescribed limits of the uniform sheet length in response to the cylically incremented and decremented actual sheet length signal. A positioning motor corrects the sheet length error if it is determined to be outside the prescribed limits. Digital means simulate the correction of sheet length error effected by the positioning motor and correct the actual sheet length signal as a function thereof.