US 6,281,679 B1Granted

Web thickness measurement system

AssigneeHoneywell-Measurex Corporation

InventorsHarriss T. King, Peter Haefner

Life of this patent

Estimating the term…

Loading patent…

Abstract

A non-contacting thickness measurement apparatus is described, which is capable of on-line, highly accurate web thickness measurements. The apparatus is comprised of a first and second distance determining means which calculate a distance value from each distance determining means to the web surface. The distance determining means are on opposite sides of the web, so each measures the distance to a different side of the web. At the same time, the distance between the two distance determining means is measured to produce a z-sensor spacing value. The two distance values are thereafter subtracted from the z-sensor spacing value to get a web thickness value. An x-y position adjustment means is used to keep the measurement spot on the web for the two distance determining means at the same location on the web, and several techniques are combined to eliminate temperature-induced and/or other unknown variations or drifts in the web thickness value which are not caused by actual changes in the thickness of the web.

Claims28

Dependent claims

A system for precision measurement of the thickness of a web having a first and second side, the system comprising:

a first mounting head disposed adjacent to the first side of the web, the first mounting head having:
a first distance sensor operative to determine a first distance between the first sensor and the first side of the web;
and
a first position sensor operative to determine the position of the first distance sensor relative to the first side of the web;
a second mounting head disposed adjacent to the second side of the web, the second mounting head having:
a second distance sensor operative to determine a second distance between the second sensor and the second side of the web;
and
a second position sensor operative to determine the position of the second distance sensor relative to the second side of the web;
a sensor positioning mechanism attached to the first and second distance sensors, the sensor positioning mechanism operative to adjust the position of the first and second distance sensors in response to the location of the first and second distance sensors determined by respective first and second position sensors;
and
a third distance sensor mounted to the first and second mounting heads and operative to determine a third distance between the first and second mounting heads wherein the thickness of the web is determined by subtracting the first and second distances from the third distance such that any error in measuring the first and second distances is mitigated by the sensor positioning mechanism.

8 more elements

A web measurement system for measuring a thickness of a web having a first and second side, the system comprising:

a first frame;
at least one first distance sensor mounted to the first frame and operative to determine a distance from the first frame to the first side of the web;
a first sensor positioning mechanism attached to the frame and the at least one first distance sensor, the first sensor positioning mechanism operative to direct the at least one first distance sensor to a prescribed location on the first side of the web;
a second frame;
at least one second distance sensor mounted to the second frame and operative to determine a distance from the second frame to the second side of the web;
a second sensor positioning mechanism attached to the frame and the at least one second distance sensor, the second sensor positioning mechanism operative to direct the at least one second distance sensor to the prescribed location on the second side of the web;
and
a third distance center attached to the first frame and the second frame, the third distance sensor operative to determine the distance between the at least one first sensor and the at least one second sensor;
wherein the first and second sensor positioning mechanisms are operative to direct the at least one first and second distance sensors to about the same location on respective first and second sides of the web.

6 more elements

Dependencies are inferred from the claim text.