US 6,145,211 AGranted

Contacting thickness gauge for moving sheet material

AssigneeImpact Systems, Inc.

InventorsPekka M. Typpo, Harold Welch

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Abstract

A caliper gauge for moving sheet material such as paper which measures the thickness of the paper accommodates bumps or holes in the paper by providing at least one side of the caliper gauge with a long continuous smooth arm which because of its mounting in close proximity to the moving sheet, which is partially made possible by the use of air bearings for the upper and lower portions of the gauge, provides a gradual wedge-shaped opening which thus allows the transfer of the momentum of the bump or hole in the paper to gradually overcome the inertia of the measuring arm which is pushed away from the paper. The arm itself is made of a single piece of sapphire and is universally pivoted by the use of a polyimide material adhered to the top of the arm which gives the arm at least 2.degree. of dimensional freedom while still maintaining it aligned in the moving direction of the paper.

Claims15

Dependent claims

A contacting thickness gauge for moving sheet material having imperfections in the form of bumps or holes which may cause tears when passing through the gauge comprising:

upper and lower air bearings on opposite sides of the sheet for carrying first and second magnetic circuit means for measuring said thickness;
said upper and lower air bearings including a plurality of spaced air exits tending to flatten a portion of said sheet encompassed by said air bearings and to provide a relatively small gap through which said sheet passes;
one of said upper and lower air bearings including a continuous smooth arm having two ends with one end including said first magnetic circuit means having a magnetic pole piece in line contact (2l) with said moving sheet, and the other end being universally pivoted on said air bearing in close proximity to said sheet, said arm forming a continuous, gradual, smooth wedge-shaped opening for said moving sheet and having a length much greater than said line contact to minimize measurement errors due to pivoting of said arm caused by movement of said material perpendicular to its moving direction.

Dependencies are inferred from the claim text.