Optical waveguides – With disengagable mechanical connector – Optical fiber/optical fiber cable termination structure
Reexamination Certificate
1999-07-21
2001-10-16
Palmer, Phan T. H. (Department: 2874)
Optical waveguides
With disengagable mechanical connector
Optical fiber/optical fiber cable termination structure
C385S086000, C385S076000, C385S053000
Reexamination Certificate
active
06302594
ABSTRACT:
TECHNICAL FIELD
The present invention relates to optical fiber technology. More particularly, it relates to the provision of a connector fitting that is adapted to be mechanically attached to the end of an optical fiber cable.
BACKGROUND OF THE INVENTION
Optical fibers are used extensively in state-of-the-art systems for transmitting information rapidly from one location to another. In these systems, the optical fibers are at their ends connected to other optical fibers or to optical devices. To ensure quality transmission of the information, it is necessary to construct the connections in a way that will minimize connection losses. According to conventional practice, end portions of two optical fiber cables are connected together with confronting ends of their optical fibers aligned and in contact with each other. An end portion of an optical fiber cable is connected to an optical device with its optical fiber in contact with an optical surface on the optical device. Connection fittings are provided at the cable ends to facilitate making the connections.
It is known to use a connector fitting that includes a ferrule having a small diameter center opening through which a bared length of optical fiber extends. The bared optical fiber and a portion of the cable axially inwardly of it are connected to the connector fitting by use of an epoxy glue. The epoxy glue is placed into a tubular inner end socket portion of the fitting. Then, the bared end portion of the optical fiber is inserted into the inner end of the fitting and moved outwardly through the epoxy glue into and through the center opening in the ferrule. After the epoxy glue has set, the bared optical fiber is cleaved flush with the outer end of the ferrule and the cut end is polished.
In the conventional way of connecting the optical fiber cable to the connector fitting, the epoxy glue that is used requires a long period of time to cure. In order to shorten the curing time, a heat gun is sometimes used but its use requires that there be a power source present to operate the heat gun. Sometimes the bared optical fiber is not properly inserted into the tubular rear portion of the connector fitting. This makes it necessary to remove the epoxy and start over in the making of the connection. There is a waste of epoxy glue and it is hard to cut and polish the optical fiber when there is epoxy on the ferrule.
A principal object of the present invention is to provide a mechanical connection of the optical fiber cable to the connector fitting, that is adapted to provide stability to the cutting of the optical cable. It is another object of the present invention to provide a connection fitting for the end of the fiber optical cable that can be installed either with or without using epoxy glue.
BRIEF SUMMARY OF THE INVENTION
The present invention is basically characterized by the use of an elongated tubular buffering sleeve between a connector fitting and an end portion of an optical fiber cable. The optical fiber cable includes an optical fiber that is surrounded by an annular buffer and an annular outer jacket. The cable is trimmed back at its end to provide a length of bared optical fiber extending axially outwardly from a length of optical fiber and buffer. The connector fitting comprises a tubular ferrule having a center opening and a tubular socket extending axially inwardly of the fitting from the ferrule. The trimmed back end of the optical fiber cable is inserted into the tubular buffering sleeve through an inner end opening. It is then moved outwardly to place the length of optical fiber and buffer inside the buffering sleeve and cause the bared length of optical fiber to project outwardly forwardly of the buffering sleeve. Then, the outer end portion of the buffering sleeve is crimped onto the length of optical fiber and buffer that is inside the buffering sleeve. Next, the bared optical fiber is inserted into the tubular socket at the inner end of the connector fitting and is moved outwardly into and through the center opening in the ferrule. The optical fiber cable and buffering sleeve are moved outwardly until the buffering sleeve is within the socket at the inner end of the connector fitting. Then, the inner end portion of the socket is crimped onto the inner end portion of the buffering sleeve.
The buffering sleeve supports the bared length of optical fiber so that it is not in a floating state when it is cut. This cutting occurs after the end portion of the cable and the buffering sleeve have been inserted into the tubular inner end portion of the connector fitting. When these parts are together, and the inner end portion of the fitting has been crimped onto the inner end portion of the buffering sleeve, an outer end portion of the bared optical fiber projects axially outwardly from the ferrule. The projecting portion of the bared fiber is cleaved and its cut end is polished.
According to an aspect of the invention, the tubular buffering sleeve includes an interior diameter in its outer end portion that is sized such that when the outer end portion of the buffering sleeve is crimped, it firmly grips the length of optical fiber and buffer that is in it.
According to another aspect of the invention, the fitting includes an outer sidewall portion that surrounds the buffering sleeve and with it forms an annular socket opening. The fiber optical cable includes an annular boot having an outer end portion. The annular boot is moved on the cable to move the outer end portion of the boot into the annular socket in the fitting.
The use of the buffering sleeve between the end of the fiber optical cable and the connector fitting makes it possible to mechanically connect the fitting to the fiber optical cable in such a way that enhances the stability of fiber slicing and otherwise facilitates the assembly operation.
Other objects, advantages and features of the invention will become apparent from the description of the best mode set forth below, from the drawings, from the claims and from the principles that are embodied in the specific structures that are illustrated and described.
REFERENCES:
patent: 6178283 (2001-01-01), Weigel
Barnard Delbert J.
Fiberon Technologies, Inc.
Palmer Phan T. H.
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