Glass manufacturing – Processes of manufacturing fibers – filaments – or preforms – With measuring – controlling – sensing – programming – timing,...
Reexamination Certificate
1998-10-06
2001-11-13
Colaianni, Michael (Department: 1731)
Glass manufacturing
Processes of manufacturing fibers, filaments, or preforms
With measuring, controlling, sensing, programming, timing,...
C065S376000, C065S268000, C065S292000, C065S296000, C065S491000, C065S425000
Reexamination Certificate
active
06314765
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to the controlling of the shape and position of a deformable object. More particularly, the present invention relates to an apparatus and a method for controlling the shape and position of an object that is deformable by the application of an outside force.
2. Discussion of Related Art
The present invention is particularly useful for controlling the shape and position of an optical fiber preform. In the prior art, it is known to control the diameter of an optical fiber preform during deposition of glassy layers therein by controlling the pressure within the bore of the preform. An example of such a method is given in U.S. Pat. No. 4,280,829. In such a method, during deposition of the glassy layers, a moving hot zone is generated within the preform while reactant gases flow through the bore of the preform in order to form uniform glassy deposits within the preform. An outer diameter monitor measures the diameter of the preform and provides a signal corresponding to the measured diameter to a controller. The controller compares the signal corresponding to the measured diameter to a set point and provides a control signal to a mass flow controller. By varying the flow of gas into the bore of the preform, the pressure within the preform is maintained at the level necessary to provide the desired preform diameter.
The prior art method has several deficiencies. Often, the locally heated portion of the preform becomes distorted and deviates from the desired shape in ways other than having a diameter which does not match the set point. Such distortion may include a non-circular cross section and/or the preform is not symmetrically disposed about the axis of rotation. Such distortion makes drawing an optical fiber from the preform difficult, if not impossible. Regulating the pressure of the gases within the bore of the preform will not correct these types of distortions.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a method for controlling the shape and position of an object, such as a cylindrical glass body.
The foregoing objective is realized by the apparatus according to the present invention which includes a heat source for heating at least a portion of the object to a temperature sufficient to render the heated portion deformable by a force, and one or more imaging devices for providing actual image signals corresponding to actual image profiles of the heated portion of the object within the field of view of the imaging devices. The apparatus also has a controller for receiving the actual image signals, for comparing the actual image signals to a reference image signal corresponding to a reference profile to obtain error image signals, and for providing an instruction signal based on the error image signals. Finally, the apparatus has a force applicator for applying a radial force to at least one distinct predetermined radial location on the heated portion of the object in response to the instruction signal to cause the heated portion of the object to conform to the reference profile.
The foregoing objective is also realized by the method of the present invention which begins by providing an object having an axis about which the object is rotated. A portion of the object is heated to a temperature sufficient to render the heated portion deformable by a force. The heated portion of the object is imaged radially by one or more imaging devices to obtain image profiles of the heated portion of the object, which are compared to a reference profile to obtain error profiles. Finally, a radial force is applied to at least one distinct predetermined radial location on the heated portion of the object in response to the error profiles to cause the heated portion of the object to conform to the reference profile.
Other objects and advantages of the present invention will become apparent to those skilled in the art from the following detailed description read in conjunction with the attached drawings and claims appended hereto.
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High-Speed Measurement and Control of Fiber-Coating Concentricity By: D.H. Smithgall & R.E. Frazee, May 19, 1981, pp. 2065-2080 The Bell System Technical Journal, Nov. 1981.
Charlton Roger
Fletcher Daniel G.
Giebner Charles A.
Alcatel
Colaianni Michael
Ware Fressola Van der Sluys & Adolphson LLP
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