Apparatus for measuring the thickness of a roll winding on or unwinding from a core

Abstract

An apparatus for measuring the thickness of a roll winding on or unwinding from a core during winding or unwinding of a web, comprises a first detector having a beam projector and a beam receiver which are arranged along the core at opposite ends of the roll for detecting a predetermined thickness of the roll with a rough accuracy. A second detector having a beam projector and a linear array sensor is provided, for detecting the roll thickness with high accuracy. When the first detector detects a predetermined thickness of the roll, the second detector, which is supported on an arm carrying a positioning roller, is placed in operative position by pressing the positioning roller against the core and detects the thickness of the roll according to the position on the linear array sensor of the beam reflected from the surface of the roll.

Dependencies are inferred from the claim text.