Optical waveguides – With disengagable mechanical connector – Optical fiber/optical fiber cable termination structure
Reexamination Certificate
1999-03-30
2002-03-19
Spyrou, Cassandra (Department: 2872)
Optical waveguides
With disengagable mechanical connector
Optical fiber/optical fiber cable termination structure
C385S062000
Reexamination Certificate
active
06357933
ABSTRACT:
TECHNICAL FIELD
The present invention is generally related to an optical fiber ferrule connector. More particularly, the present invention is an apparatus and method for a quick-connect optical fiber ferrule connector.
BACKGROUND OF THE INVENTION
Optical fiber connectors and splices are an essential part of optical fiber communications systems. Connectors may be used to join lengths of optical fiber into longer lengths, or to connect optical fiber to active devices such as radiation sources, detectors, or repeaters, or to passive devices such as switches or attenuators.
An optical fiber connector must meet at least two requirements. It must couple or join two optical fibers with minimum insertion loss. Secondly, it must provide mechanical stability and protection to the junction between the optical fibers in the working environment. Achieving low insertion loss in coupling two optical fibers is generally a function of the alignment of the optical fiber ends, the width of the gap between the ends, and the optical surface condition of the ends. Stability and junction protection is generally a function of connector design, such as, for example, the minimization of differential thermal expansion effects.
Many approaches to achieving fiber alignment can be found in the prior art. Among them are V-grooves, resilient ferrules, and conical bushings. A discussion of prior art connectors is provided in R. Schultz,
Proceedings of the Optical Fiber Conference,
Los Angeles (September 1982), pp. 165-170.
A further consideration in connector design is the relative ease of field installation of the connector. It is desirable that a sought-after connector be capable of being installed within a relatively short period of time without requiring special skills or manipulations not easily carried out in the field. Further, it is desired that an optical fiber connector be capable of field-terminating a length of optical fiber.
Many optical fiber connectors require the use of adhesives or epoxies in securing connector components in the field. For example, a typical connector includes a ferrule piece rigidly fixed to a connector body. Adhesive is injected into a longitudinal bore of the ferrule prior to inserting the optical fiber to be connected. A cable is received into the connector body with the enclosed fiber projecting along the longitudinal bore of the ferrule. This adhesive typically must be heat cured. As such, heat curing ovens are required in the field where the connectors are being installed and a power source for those ovens must be available. Additionally, the heat curing takes time both to heat and to cool down.
A known optical fiber connector that implements the use of adhesive is an SC connector. The SC connector includes a ferrule assembly which has a barrel with a collar at one end and an optical fiber terminating ferrule extending from the other end of the barrel. The ferrule assembly is disposed in a plug frame such that an end portion of the ferrule, terminating at an end face, projects from one end of the plug frame and a strength member retention portion of a cable retention member is disposed over the barrel projecting from the other end. During termination, adhesive is inserted into a bore in the barrel followed by the insertion of a fiber until the fiber exits the ferrule assembly at the end face of the terminating ferrule. The fiber can then be cleaved and polished as necessary. Because of the curing process, and further because of the overall difficulties inherent in the use of adhesives, there is a desire to adapt the SC connector as well as other optical fiber connectors for use without adhesives or epoxies.
However, the adhesiveless or epoxiless configurations of the prior art often suffer from decreased optical performance as a result of “pistoning.” Pistoning is the alternating expansion and contraction of the ferrule and/or barrel of a connector typically due to temperature variations. This expanding and contracting results in the longitudinal movement of the cleaved end of the fiber within the bore of the connector, specifically within the ferrule and relative to the end face. The negative effects of “pistoning” have been addressed with the implementation of fiber protrusion. Fiber protrusion refers to a cleaved end of a fiber that extends, or protrudes, beyond the end face of the ferrule of the connector. While this configuration reduces the negative effect of “pistoning” on the optical performance of the connector, the protruding fiber portion is exposed to debris and susceptible to cracks and breakage. Thus, a connector for use without adhesives or epoxies and that minimizes or eliminates “pistoning” without the need for fiber protrusion is desirable to the industry.
Thus, a heretofore unaddressed need exists in the industry to address the aforementioned deficiencies and inadequacies to produce an adhesiveless connector that is not subject to these drawbacks.
SUMMARY OF THE INVENTION
Certain advantages and novel features of the invention will be set forth in the description that follows and will become apparent to those skilled in the art upon examination of the following or may be learned with the practice of the invention.
The present invention is generally directed to a quick connect optical fiber ferrule connector that can be installed in the field without the use of adhesive or epoxy. The connector includes a ferrule having a receiving end, a terminating end, and a tapered ferrule bore disposed and extending therethrough. The tapered ferrule bore has a larger diameter toward the fiber receiving end than toward the connection or terminating end. Also included is a barrel having a barrel bore disposed therein. The barrel is arranged and configured to receive the receiving end of the ferrule such that the barrel bore and the ferrule bore are axially aligned. An insert having a receiving end, a support end, and a bore disposed therethrough is positioned such that the receiving end of the insert is disposed within the barrel bore and the support end of the insert is disposed within the tapered ferrule bore. The support end is compressible and the insert is tapered such as to correspond with the tapered ferrule bore.
The invention can be viewed as providing a method for installing a fiber optic connector in the field without using adhesives. In this regard, the method can be summarized broadly by the following steps. A ferrule assembly is provided having a ferrule disposed partially within a barrel such that a tapered ferrule bore is axially aligned with a barrel bore disposed within the barrel. An insert, having a bore disposed therethrough, is provided and slidably disposed within the tapered ferrule bore and the barrel bore. The insert has a taper that corresponds to the tapered ferrule bore. The insert includes a compressible support end. In the field, a fiber is inserted into the bore of the insert until the fiber exits the ferrule. Finally, the ferrule assembly is compressed longitudinally such that the ferrule is pushed further into the barrel and the insert moves toward the ferrule. The tapered bore of the ferrule compresses the support end of the insert thereby fixing the fiber in the ferrule assembly through the gripping action of the insert.
Other features and advantages of the present invention will become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional features and advantages be included herein within the scope of the present invention.
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patent: 5943460 (1999-08-01), Mead et al.
“Quick-connect fiber-optic conne
Bradley Kelvin B.
Gibbs Gary F.
Pierce Charles O.
Lucent Technologies - Inc.
Spyrou Cassandra
Thomas Kayden Horstemeyer & Risley LLP
Treas Jared
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