Sheet tension sensor

A sheet tension sensor for determining the tension of a moving sheet, comprising:

• a first pair of opposing surfaces adapted for pressurized sliding contact with opposite sides of the moving sheet;
• a second pair of opposing surfaces adapted for contact with the opposite sides of the moving sheet, wherein the second pair of surfaces are spaced from the first pair of surfaces;
• a sheet deflection member disposed between the first and second pairs of opposing surfaces to forcibly deflect the sheet as the sheet moves between the first and second pairs of opposing surfaces;
• and
• a deflection sensor adapted to generate a deflection signal indicative of the amount of sheet deflection induced in the sheet by the member.

A sheet tension sensor for determining the tension of a moving sheet, comprising:

• a first pair of opposing surfaces adapted for pressurized sliding contact with opposite sides of the moving sheet;
• a second pair of opposing surfaces adapted for contact with the opposite sides of the moving sheet, wherein the second pair of surfaces are spaced from the first pair of surfaces;
• a sheet deflection member disposed between the first and second pairs of opposing surfaces to forcibly deflect the sheet as the sheet moves between the first and second pairs of opposing surfaces;
• and
• a force sensor adapted to generate a force signal indicative of the force exerted by the deflection member against the sheet.

A process for measuring the tension in a moving sheet, comprising the steps of:

• at a first location, moving the sheet between two surfaces in sliding contact with opposite sides of the sheet;
• deflecting a portion of the sheet at a location which is spaced from the first location in the direction of sheet movement;
• and
• determining sheet tension based upon the amount of deflection and the magnitude of the deflecting force.

A scanning sheet tension sensor, comprising:

• a first pair of opposing surfaces disposed for contact with opposite sides of a sheet;
• a second pair of opposing surfaces disposed for contact with the opposite sides of the sheet, wherein the second pair of surfaces is spaced from the first pair of surfaces;
• a sheet deflection member disposed between the first and second pairs of opposing surfaces for forcibly deflecting the sheet;
• a deflection sensor adapted to generate a deflection signal indicative of the amount of sheet deflection induced in the sheet by the member;
• a force sensor adapted to generate a force signal indicative of the force exerted by the deflection member on the sheet;
• and
• scanning means for scanning the sheet deflection member and the first and second pairs of opposing surfaces back and forth across the width of the sheet.