Optical waveguides – With disengagable mechanical connector – Optical fiber/optical fiber cable termination structure
Reexamination Certificate
2000-01-18
2003-05-20
Lee, John D. (Department: 2674)
Optical waveguides
With disengagable mechanical connector
Optical fiber/optical fiber cable termination structure
C385S060000, C385S072000, C385S076000
Reexamination Certificate
active
06565264
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to fiber optic termini, and more particularly to pin and socket fiber optic termini. By pin and socket termini is meant termini of the type in which a pair of optical fibers are connected by installing each fiber in a hole in a precision ferrule, and positioning the ferrules in alignment with their tips abutting. A first or socket ferrule lies in the rear half of an alignment sleeve of a socket connector, and a pin connector is mated to the socket connector by projecting the pin ferrule into the sleeve until the tips of the ferrules abut, the socket ferrule being spring biased forwardly so it can deflect rearwardly.
In addition to relating to improved pin and socket termini, the present invention relates to a method of terminating fiber optic cables to fiber optic termini.
2. Description of the Related Art
Pin and socket fiber optic termini of the type in which a pair of optical fibers are connected by installing each fiber in a hole in a precision ferrule, and positioning the ferrules in alignment with their tips abutting, are well known and widely used. However, conventional pin and socket fiber optic termini have a number of limitations which makes them impractical for use in couplers requiring a terminus size of less than size 16. The present invention is directed to the following improvements to the conventional pin and socket fiber optic termini, which are intended to simplify manufacture and thereby enable production of smaller termini: (i) re-design of the holders or retention sleeves, precision ceramic guides, and biasing arrangements for the termini to permit the holders and guides to be press-fit together, avoiding the need to use adhesives or laser welds during assembling of the terminus structures (although adhesives may still be used during termination of the fiber optic cables to the pin and socket termini); (ii) re-design of the portion of the termini to which the strength members of the cable are terminated, simplifying the termination procedure and providing a more secure termination; (iii) including features that facilitate replacement of parts, cleaning and polishing of the mating faces of the precision guides or ferrules after a cable has been terminated thereto, and formation of a good environmental seal at the ingress of the terminated cable into a pin and socket coupler.
FIGS. 1A and 1B
illustrate a conventional pin and socket fiber optic connector system. The conventional termination arrangement includes a pin connector
1
and a socket connector
2
arranged to accommodate a plurality of pin termini
3
,
3
′ and socket termini
4
,
4
′. Pin termini
3
,
3
′ and socket termini
4
,
4
′ are arranged so that the pin and socket connectors can conveniently be mated by simply inserting ends of the pin termini
3
,
3
′ into openings in the socket termini
4
,
4
′ and then securing the pin connector
1
to the socket connector
2
using any of a variety of known coupling means (not shown). Examples of known types of coupling means that can be used in connection with pin and socket fiber optic termination arrangements of the illustrated type include threaded coupling nuts and bayonet-type coupling arrangements.
One of the pin termini
3
of the connector system of
FIG. 1A
is shown prior to mating and another of the pin termini
3
′ is shown in a mated position. Each pin terminus includes a ceramic guide
5
for precisely locating an optical fiber, and a guide holder
6
, conventionally made of stainless steel, for holding the ceramic guide. The retention sleeve
6
is conventionally secured to the precision guide by adhesives or welding, and includes an integral rear ferrule to which the strength member and/or jacket of the cable is terminated after being stripped back from the fiber, and after insertion of the fiber through the retention sleeve
6
into the precision guide
5
. The completed pin termini are mechanically held in the pin connector
1
by retention tines
8
that engage a collar
9
on the retention sleeve, and the coupler is completed by the inclusion of a sealing gasket
11
at the mating interface of the pin coupler, and a sealing grommet
12
that engages the rear of the retention sleeve
6
and cable jacket
7
extending therefrom to prevent ingress of moisture or dust into the coupler.
The socket termini
4
,
4
′, shown in greater detail in
FIG. 1B
, also include precision ceramic guides
13
and guide retention sleeves
15
to which strength members and/or jackets
16
of the fiber optic cables are terminated, and in addition includes an arrangement for biasing the retention sleeve
15
and guide
13
of respective socket termini
4
,
4
′ against the retention sleeve
6
and guide
5
of corresponding pin termini
3
,
3
′. Furthermore, the socket termini
4
,
4
′ each includes a biasing arrangement in the form of a compression spring
17
that engages a rear of the corresponding retention sleeve
15
and is captured between the retention sleeve
15
and a rear ferrule or cap
18
to which the cable is terminated. Rear ferrule
18
is secured, through use of an adhesive or welding, to an alignment sleeve
19
which axially aligns the ceramic guides of the pin and socket connectors, and which surrounds the retention sleeve
15
to guide the retention sleeve while permitting axial movement of the retention sleeve during mating.
An opening
20
in the alignment sleeve serves as the socket opening for receiving corresponding precision guide
5
of one of the pin termini
3
,
3
′. The socket termini
2
are secured in the socket connector, in the illustrated connector system, by engagement between a collar
21
on the alignment sleeve
19
, and retention tines
22
similar to the corresponding retention tines of the pin connector, although it is also possible to arrange the rear ferrule
18
to engage the retention tines. At the rear of retention sleeve
15
is a space
23
′ that permits movement of guide
13
and retention sleeve
15
in a rearward direction against the bias provided by spring
17
in response to insertion of guide
5
into alignment sleeve
19
. Conventionally, the strength member of the cable is secured to a rear portion of rear ferrule member
18
by crimp ferrule
25
, and a sealing rear grommet
23
corresponding to sealing grommet
12
is provided at the rear of the socket connector
2
to complete the connector system.
As mentioned above, the design illustrated in
FIG. 1
, as well as other similar pin and socket fiber optic termination designs, are impractical for terminus sizes of less than 16. One reason is that the precision ceramic guide and guide retention sleeve of the conventional pin and socket termini (or the alignment sleeve and rear ferrule or cap of the conventional socket terminus), must be secured to each other through use of adhesives or precision welding techniques. The design of the socket terminus, in particular, necessitates the use of adhesives or welding because of the manner in which the bias spring is captured within the alignment sleeve. This use of adhesives or welding becomes increasingly difficult to carry out as the terminus size is decreased, resulting in increased assembly costs and likelihood of errors. Furthermore, once the rear ferrule is adhered or welded to the alignment sleeve, non-destructive removal of the precision guide from the assembly is impossible. As a result, should an error occur during assembly or cable termination, or should one of the parts of the terminus prove defective, the entire terminus must be discarded, further increasing costs.
A second problem that arises in smaller fiber optic terminations is that a smaller termination area for the cable strength member makes termination of the cable to the terminus difficult. Conventional designs do not leave sufficient room to provide a secure mechanical termination of the strength member to the rear of the guide retention sleeve in the pin terminati
Gallusser David Otis
Johnson Heath Allen
Mikolaicyk John Henry
Olesik Gregory John
Amphenol Corporation
Blank Rome LLP
Lee John D.
Song Sarah U
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