US 5,015,867 A · Apparatus and methods for measuring the diameter of a moving elongated material

Abstract

The present invention relates to an apparatus and methods for measuring the diameter variation of an elongated cylindrically shaped object. In particular, the instant invention relates to measuring the diameter variation of a moving strand comprised of multiple textile filaments. Using lasers and charged coupled devices (hereinafter referred to as "CCD's") for sensing the diffraction and interference patterns produced when electromagnetic radiation emitted from at least one laser is partially obscured by the edges of the strand. Several methods for extracting the information contained in the diffraction pattern may be employed. One method is based upon a comparison between the measured diffraction pattern and a theoretical pattern produced by a knife edge as calculated using the Kirchhoff-Fresnel integral. Others rely upon comparing the measured diffraction pattern with patterns previously produced by cylindrical objects of known diameter and stored in a computer library. The remaining methods are empirically based and may be implemented by algorithms which should be available on any small personal computer capable of performing a statistical analysis of data stored in an array or vector form. A feedback system for controlling the temperature of a fiber glass bushing assembly based on changing diameter measurements collected by the aforesaid apparatus is also disclosed.

Claims29

Dependent claims

A method for measuring the diameter variation of a substantially continuous length of opaque, moving, elongated material comprising the steps of:

(a) passing said elongated material substantially perpendicular to and within the path of at least one pulsed beam of electromagnetic radiation, each said at least one pulsed beam emitted by a separate semiconductor laser so as to generate two independent diffraction patterns simultaneously from the edges of said elongated material and an interference pattern due to the interaction of said diffraction patterns with one another;
(b) registering the intensity of said diffraction and interference patterns upon the surface of an array type charge coupled device positioned so as to interrupt the path of each said at least one pulsed beam, each said device possessing a plurality of discrete pixel elements thereon capable of producing an electrical charge proportional to the intensity of the diffraction and interference patterns;
(c) converting the electrical charge within each pixel element into an analog electrical signal proportional to the intensity of the diffraction and interference patterns registered within each pixel element;
(d) converting said analog electrical signal into a digital representation;
(e) processing and storing said digital representation as a first vector array in a computer memory;
and
(f) processing said vector array so as to calculate the diameter of said elongated material.

4 more elements

An apparatus for measuring the diameter variation of a substantially continuous length of opaque, moving, elongated material comprising:

a. a dimensionally stable optical table having an opening centrally located therein with a slot extending from said opening to the periphery of said table;
b. an annular detection chamber positioned inside said opening, said detection chamber also having a slot along its length and aligned with the slot in said optical table so as to permit the passage of said moving elongated material from outside the periphery of said table to the interior of said detection chamber, said detection chamber also having a plurality of apertures about its circumference, each pair of said apertures being located diametrically opposite one another;
c. four pairs of semiconductor lasers and array type charge coupled devices, each said laser and charged coupled device being positioned opposite one another behind opposing apertures about the circumference of said annular detection chamber, each said laser capable of emitting a pulsed beam of electromagnetic radiation and each said charge coupled device capable of detecting the presence of said electromagnetic radiation on a sensing surface thereof;
d. a protective window covering the sensing surface of each said charge coupled device;
e. an extended hollow guide separating the protective window covering each said charge coupled device from the corresponding aperture in front of each said device so as to channel electromagnetic radiation from said aperture through said guide toward the sensing surface of said device;
f. means for positioning and guiding said moving elongated material through said annular detection chamber, the path of said elongated material being substantially perpendicular to the path of each said pulsed beam of electromagnetic radiation emitted by each said semiconductor laser whereby two independent diffraction patterns are generated simultaneously from the edges of said elongated material and an interference pattern due to the interaction of said diffraction patterns with one another is produced by each said pulsed beam and a representation of said patterns is thereby registered on the sensing surface of said corresponding charge coupled device;
and,
g. means for electronically processing said representation registered on the sensing surface of each said charge coupled device so as to calculate the diameter of said elongated material using the information contained in said diffraction and interference patterns.

5 more elements

Dependencies are inferred from the claim text.

Apparatus and methods for measuring the diameter of a moving elongated material

Life of this patent

Apparatus and methods for measuring the diameter of a moving elongated material

Life of this patent

Abstract

Claims29