Regulated length take-up device

A regulated length take-up device for continually taking up a regulated length of sheet material around a take-up roll, comprising:

• a rotating lever disposed on the take-up roll by means of a one-way clutch,
• take-up driving means, pivotably connected to the rotating lever, for rotating the take-up roll,
• a sensor lever positioned adjacent the take-up roll along a tangential direction of the take-up roll and pivoted about a pivot point according to variations in a take-up diameter of the take-up roll, and
• stroke constraint means for controlling a take-up stroke of the rotating lever in response to the variations in the take-up roll diameter so that the regulated length is kept constant, the stroke constraint means comprising:
• a stopper attached to the sensor lever and extending in an axial direction of the take-up roll, and
• a cam curvature portion of the rotating lever,
• wherein the stopper prevents the rotating lever from rotating in a restoring direction in response to a stationary holding force, and
• a shape of the cam curvature portion is selected to transfer the stationary holding force applied to the rotating lever to the sensor lever through the stopper in a direction extending toward the pivot point, such that substantially no force is applied by the rotating lever to the sensor lever in a direction toward the take-up roll.