U.S. patent number RE37,080 [Application Number 08/931,916] was granted by the patent office on 2001-03-06 for optical fiber ferrule connector having enhanced provisions for tuning.
This patent grant is currently assigned to Lucent Technologies Inc.. Invention is credited to Daniel Lee Stephenson, Ruben Travieso.
United States Patent |
RE37,080 |
Stephenson , et al. |
March 6, 2001 |
Optical fiber ferrule connector having enhanced provisions for
tuning
Abstract
An optical connector (20) includes a ferrule assembly (22),
which is adapted to be received in a plug frame (70). The ferrule
assembly is held in the plug frame by a cable retention assembly
(40) which is adapted to be secured to said plug frame. A leading
end of the plug frame is symmetrical in an end cross-section which
is normal to a longitudinal axis of the connector. After the
ferrule assembly has been assembled to the plug frame, the
direction of any eccentricity of the plug passageway or of an
optical fiber terminated by the ferrule assembly is determined.
Then the plug frame is assembled to a housing of a grip (90) such
that the direction of eccentricity is aligned with a key (92) of
the grip. The plug frame is capable of being assembled to the grip
notwithstanding the rotational orientation of the plug frame with
respect to the grip. An optical connection between optical fibers
terminated by two connectors is made by inserting the grip of each
of the two connectors into a coupling housing (100) so that the
keys are aligned. Advantageously, portions of the connector may be
factory assembled which facilitates field use of the connector to
terminate optical fiber.
Inventors: |
Stephenson; Daniel Lee
(Lilburn, GA), Travieso; Ruben (Alpharetta, GA) |
Assignee: |
Lucent Technologies Inc.
(N/A)
|
Family
ID: |
25394688 |
Appl.
No.: |
08/931,916 |
Filed: |
May 18, 1997 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
889203 |
May 27, 1992 |
05212752 |
May 18, 1993 |
|
|
Current U.S.
Class: |
385/78; 385/139;
385/56; 385/67; 385/76; 385/84 |
Current CPC
Class: |
G02B
6/3831 (20130101); G02B 6/3887 (20130101); G02B
6/3874 (20130101); G02B 6/3871 (20130101); G02B
6/3843 (20130101); G02B 6/3821 (20130101); G02B
6/3893 (20130101); G02B 6/3851 (20130101) |
Current International
Class: |
G02B
6/38 (20060101); G02B 006/26 (); G02B 006/38 () |
Field of
Search: |
;385/53,55,56,60,66,67,76,77,78,81,84,139 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Healy; Brian
Parent Case Text
.Iadd.Application Ser. No. 08/443,978, filed May 18, 1995, and
application Ser. No. 08/931,916, filed May 18, 1995, are copending
applications which are each reissue applications of application
Ser. No. 07/889,203, filed May 27, 1992, now U.S. Pat. No.
5,212,752..Iaddend.
Claims
We claim:
1. An optical fiber connector, said connector comprising:
a ferrule assembly including a ferrule portion having a passageway
for an optical fiber, and a barrel;
a plug frame in which is disposed said ferrule assembly, said
barrel of said ferrule assembly projecting toward a latching end
portion of said plug frame and said ferrule projecting toward an
opposite end portion of said plug frame.[., said opposite end
portion of said plug frame being symmetrical with respect to a
cross section of said plug frame which is normal to a longitudinal
axis of said connector.]. ;
spring means disposed about said portion of said ferrule assembly
which projects toward said latching end portion of said plug frame;
.Iadd.and.Iaddend.
.[.a cable retention member which is assembled to said plug frame
and which includes a pocket for said spring means and said barrel,
said cable retention member including outwardly projecting tabs
each of which is received in a slot in said latching end portion of
said plug frame to secure said cable retention member to said plug
frame, said cable retention means being effective to preload said
spring means, and.].
a housing in which said plug frame is disposed and which has a
longitudinal axis, said plug frame capable of being assembled to
said housing .[.in any one of a plurality of rotational
orientations with respect to the longitudinal axis of said
connector.]. .Iadd., and wherein the housing is provided with at
least one port about the circumference of an intermediate portion
thereof, each of said ports exposing the plug frame which is
inserted into said grip, said ports of said grip being enclosed by
said coupling housing when said grip is seated fully in and
coupling housing..Iaddend.
2. The optical fiber connector of claim .[.1.]. .Iadd.26.Iaddend.,
which also includes a crimp portion which includes a sleeve which
includes a large diameter portion which is capable of being crimped
about a portion of said cable retention member with portions of a
cable sheath system disposed between said large diameter portion of
said crimp portion and said cable retention member and a small
diameter portion which is capable of being crimped about a portion
of a cable.
3. The optical fiber connector of claim .[.2.]. .Iadd.4.Iaddend.,
wherein said crimp portion includes a mandrel having a portion
which becomes disposed in said large diameter portion of said
sleeve, through which extends optical fibers of a cable being
terminated and about which is disposed strength members of the
cable so that the strength members may be secured between the large
diameter portion of the sleeve and an outer surface of the cable
retention member.
4. The optical fiber connector of claim .[.2.]. .Iadd.26.Iaddend.,
wherein a central portion of said cable retention member includes
circumferentially extending tabs each of which is adapted to be
received in an opening of said plug frame to secure said cable
retention member to said plug frame..[.
5. The optical fiber connector of claim 4, wherein said connector
comprises a grip which includes said housing and which includes a
leading end portion having outer surfaces and a central cavity for
receiving said plug frame assembly and a key protecting from one of
the outer surfaces of the leading end portion of said housing, said
opposite end portion of said plug frame including four outer
orthogonal surfaces and being capable of being assembled to said
grip such that any one of said outer surfaces of said opposite end
portion of said plug frame is aligned with said key..]..[.
6. The optical fiber connector of claim 5, wherein said plug frame
is assembled to said grip to cause the direction of any
eccentricity of said passageway in said ferrule to be in the same
quadrant as said key..].
7. The optical fiber connector of claim .[.6.]. .Iadd.1.Iaddend.,
wherein said ferrule assembly includes a segmented collar with said
barrel and said ferrule portion extending from opposite sides
thereof, said plug frame including inwardly radially projecting,
circumferentially spaced splines, said ferrule assembly being
disposed in said plug frame such that grooves formed between
segmented portions of said collar receive splines of said plug
frame therebetween to prevent relative rotation between said plug
frame and said ferrule assembly..[.
8. The optical fiber connector of claim 7, wherein two opposed
inner portions of said grip of said leading end portion of said
grip are provided with inwardly projecting latching nubs, said
opposite end portion of said plug frame including a beveled surface
at the intersection of each two outer surfaces of said opposite end
portion of said plug frame, each said beveled surface being an
invert of a groove formed by sidewalls which connect to said
orthogonal surfaces of said opposite end portion of said plug
frame, whereupon assembly of said plug frame to said housing of
said grip, one of said latching nubs of said housing of said grip
becomes disposed in one of said grooves and the opposed one of said
latching nubs becomes disposed in a diagonally opposite one of said
grooves..]..[.
9. The optical fiber connector of claim 8, wherein each of said
orthogonal surfaces of said opposite end portion of said plug frame
is provided with a detent and a leading end portion of said housing
of said grip includes opposed walls and opposed openings, said
assembly of said plug frame with said housing of said grip to cause
said latching nubs of said grip to become disposed in two of said
grooves of said plug frame and the assembly of said grip with a
coupling housing causing latching fingers of said coupling housing
to snap-lock behind each of two opposed detents to secure said
connector to the coupling housing..].
10. The optical fiber connector of claim .[.9.]. .Iadd.27.Iaddend.,
wherein the arrangement of said latching nubs and said grooves in
said opposite end portion of said plug frame is such that the
application of compressive forces to diagonally opposed outer
corner portions of said housing of said grip which are aligned with
said latching nubs causes disengagement of said latching nubs with
said grooves and allows withdrawal of said plug frame from said
grip.
11. The optical fiber connector of claim .[.9.]. .Iadd.1.Iaddend.,
which also includes a cable strain relief portion having a small
diameter cable entry portion which transitions to a large diameter
end portion which is adapted to be disposed about said crimp
portion and connected to said cable retention member..[.
12. The optical fiber connector of claim 10, wherein said plug
frame is adapted to be assembled to said housing of said grip when
any one of said orthogonal surfaces of said opposite end portion of
said plug frame is aligned with the outer surface of said housing
of said grip which includes said key..]..[.
13. The optical fiber connector of claim 12, which is adapted to
become assembled to a coupling housing with said passageway of said
ferrule being aligned with a passageway of a ferrule of another
such connector which is aligned coaxially therewith in the coupling
housing..].
14. A terminated optical fiber, which includes:
a length of optical fiber; and
an optical fiber connector which terminates said length of optical
fiber, said optical fiber connector comprising:
a ferrule assembly including a ferrule portion having a passageway
for an optical fiber, and a barrel;
a plug frame in which is disposed said ferrule assembly, said
barrel of said ferrule assembly projecting toward a latching end
portion of said plug frame and said ferrule projecting toward an
opposite end portion of said plug frame, .[.said opposite end
portion of said plug frame being symmetrical with respect to a
cross section of said plug frame which is normal to a longitudinal
axis of said connector;.].
spring means disposed about said portion of said ferrule assembly
which projects toward said latching end portion of said plug
frame;
.[.a cable retention member which is assembled to said plug frame
and which includes a pocket for said spring means and said barrel
portion, said cable retention member including outwardly projecting
tabs each of which is received in a slot in said latching end
portion of said plug frame to secure said cable retention member to
said plug frame, said cable retention means being effective to
preload said spring means;.]. and
a housing in which said plug frame is disposed and which has a
longitudinal axis, said plug frame capable of being assembled to
said housing .[.in any one of a plurality of rotational
orientations with respect to the longitudinal axis of said
connector.]. .Iadd.and wherein the housing is provided with ports
spaced about the circumference of an intermediate portion thereof,
said ports exposing the plug frame which is inserted into said
grip, said ports of said grip being enclosed by said coupling
housing when said grip is seated fully in said coupling
housing.Iaddend..
15. The terminated optical fiber of claim .[.16.].
.Iadd.28.Iaddend., wherein a central portion of said cable
retention member includes circumferentially extending tabs each of
which is adapted to be received in an opening of said plug frame to
secure said cable retention member to said plug frame..[.
16. The terminated optical fiber of claim 15, which also includes a
grip which includes said housing in which said plug frame is
disposed, said housing of said grip including a leading end portion
which includes outer surfaces and which includes a central cavity
for receiving said plug frame and a key projecting from one of said
outer surfaces of said housing of said grip, said opposite end
portion of said plug frame including four outer orthogonal surfaces
and being capable of being assembled to said grip such that any one
of said outer surfaces of said opposite end portion of said plug
frame is aligned with said key..]..[.
17. The terminated optical fiber of claim 16, wherein said plug
frame is assembled to said grip to cause the direction of
eccentricity of said passageway in said ferrule to be in the same
quadrant as said key..].
18. The terminated optical fiber of claim .[.17.].
.Iadd.15.Iaddend., wherein two opposed inner portions of said grip
of said leading end portion of said grip are provided with inwardly
projecting latching nubs, said opposite end portion of said plug
frame including a beveled surface at the intersection of each two
surfaces of said opposite end portion of said plug frame, said
beveled surface being an invert of a groove formed by sidewalls
which connect to orthogonal surfaces of said opposite end portion
of said plug frame, whereupon assembly of said plug frame to said
housing of said grip, one of said latching nubs of said housing of
said grip becomes disposed in one of said grooves and the opposed
one of said latching nubs becomes disposed in a diagonally opposite
one of said grooves..[.
19. An optical fiber connection, which includes: a coupling
housing; and
two terminated optical fibers, each being a terminated optical
fiber as set forth in claim 14..]. .[.
20. The optical fiber connection of claim 19, wherein a central
portion of said cable retention member includes circumferentially
extending tabs each of which is adapted to be received in an
opening of said plug frame to secure said cable retention member to
said plug frame..]..[.
21. The optical fiber connection of claim 20, which also includes a
grip which includes said housing in which said plug frame is
disposed, said housing which includes outer surfaces and which
includes a central cavity for receiving said plug frame assembly
and a key projecting from one of said outer surfaces of a leading
end portion of said housing of said grip, said opposite end portion
of said plug frame including four outer orthogonal surfaces and
being capable of being assembled to said grip such that any one of
said outer surfaces of said opposite end of said plug frame is
aligned with said key..]..[.
22. The optical fiber connection of claim 21, wherein said plug
frame is assembled to said grip to cause the direction of
eccentricity of said passageway in said ferrule to be in the same
quadrant as said key..]..[.
23. The optical fiber connection of claim 22, wherein two opposed
inner portions of said grip of said leading end portion of said
grip are provided with inwardly projecting latching nubs, said
opposite end portion of said plug frame including a beveled surface
at the intersection of each two orthogonal surfaces of said
opposite end portion of said plug frame, said beveled surface being
an invert of a groove formed by sidewalls which connect to
orthogonal surfaces of said opposite end portion of said plug
frame, whereupon assembly of said plug frame to said housing of
said grip, one of said latching nubs of said housing of said grip
becomes disposed in one of said grooves and the opposed one of said
latching nubs becomes disposed in a diagonally opposite one of said
grooves..]..[.
24. The optical fiber connection of claim 23, wherein said grip is
provided with ports spaced about the circumference of an
intermediate portion thereof, said ports exposing the plug frame
which is inserted into said grip, said ports of said grip being
enclosed by said coupling housing when said grip is seated fully in
said coupling housing..]..[.
25. The optical fiber connection of claim 24, wherein said coupling
horsing includes opposed latching fingers at each end portion
thereof and said plug frame includes a detent disposed along each
of said four outer orthogonal surfaces such that when said grip is
inserted into one end of said coupling housing, the latching
fingers associated with said one end of said housing are moved into
openings in said housing of said grip and snap-lock behind detents
of said plug frame to secure said grip to said coupling
housing..]..Iadd.
26. The optical fiber connector of claim 1, which also includes a
cable retention member which is assembled to said plug frame and
which includes a pocket for said spring means and said barrel, said
cable retention member including outwardly projecting tabs each of
which is received in a slot in said latching end portion of said
plug frame to secure said cable retention member to said plug
frame, said cable retention means being effective to preload said
spring means..Iaddend..Iadd.
27. The terminated optical fiber of claim 1, wherein two opposed
inner portions of said grip of said leading end portion of said
grip are provided with inwardly projecting latching nubs, said
opposite end portion of said plug frame including a beveled surface
at the intersection of each two surfaces of said opposite end
portion of said plug frame, said beveled surface being an invert of
a groove formed by sidewalls which connect to orthogonal surfaces
of said opposite end portion of said plug frame, whereupon assembly
of said plug frame to said housing of said grip, one of said
latching nubs of said housing of said grip becomes disposed in one
of said grooves and the opposed one of said latching nubs becomes
disposed in a diagonally opposite one of said
grooves..Iaddend..Iadd.
28. The terminated optical fiber of claim 14, which also includes a
cable retention member which is assembled to said plug frame and
which includes a pocket for said spring means and said barrel, said
cable retention member including outwardly projecting tabs each of
which is received in a slot in said latching end portion of said
plug frame to secure said cable retention member to said plug
frame, said cable retention means being effective to preload said
spring means..Iaddend..Iadd.
29. The optical fiber connector of claim 18, wherein the
arrangement of said latching nubs and said grooves in said opposite
end portion of said plug frame is such that the application of
compressive forces to diagonally opposed outer corner portions of
said housing of said grip which are aligned with said latching nubs
causes disengagement of said latching nubs with said grooves and
allows withdrawal of said plug frame from said grip..Iaddend.
Description
TECHNICAL FIELD
This invention relates to an optical fiber ferrule connector having
enhanced provisions for tuning. More particularly, the invention
relates to an SC connector which includes enhanced provisions for
tuning eccentricity of an optical fiber core or fiber-receiving
passageway in the ferrule.
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 in
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.
Some prior art optical fiber connectors contain one or more
precision-machined parts and therefore are relatively costly items.
Whereas this may be acceptable for some applications, in other
cases the cost of such prior art connectors might constitute a
significant fraction of the total installation cost. Thus, strong
incentives exist for providing optical fiber connectors that do not
require expensive precision-machined parts.
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.
A prior art connector which has many of the above-listed desirable
features includes two drawn glass cylindrical plugs or ferrules,
with a fiber end portion inserted into a close-fitting passageway
of each ferrule, and the connection between the two fiber ends made
by inserting the ferrules in end-to-end fashion into an alignment
sleeve that maintains the outer surfaces of the two ferrule in
registry. This connector design relies on the capability of
producing ferrules to very close tolerances by drawing them from a
glass preform. Relative rotation of the two ferrules typically
changes the relative position of the fibers held within the
passageway because of the eccentricity of the optical fiber core
which respect to the ferrule. Eccentricity is defined as the
distance between the longitudinal centroidal axis of the ferrule at
an end face of the ferrule and the centroidal axis of the optical
fiber core held within the passageway of the ferrule. Generally,
the passageway is not concentric with the outer cylindrical surface
which is the reference surface. Also, the optical fiber may not be
centered within the ferrule passageway and the fiber core may not
be concentric with the outer surface of the fiber. Hence, the
eccentricity is comprised of the eccentricity of the optical fiber
within the ferrule passageway and the eccentricity of the
passageway within the ferrule.
Because it is very difficult to control the eccentricity of the
optical fiber core in the ferrule in which it is terminated, it is
difficult to achieve desired losses of 0.1 dB or less in single
mode fibers without maintaining close tolerances so that the
opposed cores are aligned to within about 0.7 .mu.m. This, of
course, increases manufacturing costs.
If the total eccentricities of the two optical fiber ends to be
joined are identical or at least very nearly so, then a low-loss
connection can be achieved by merely rotating, within the alignment
sleeves, one ferrule with respect to the other, until maximum
coupling is observed.
Central to a so-called prealigned rotary splice is the recognition
that eccentricity between ferrule passageway and ferrule
cylindrical surfaces essentially will have no effect on alignment
of fibers terminated by two ferrules if the two ferrules have
essentially the same amount of passageway eccentricity relative to
the cylindrical surfaces and if the ferrules are aligned such that
the eccentricities are in the same radial direction from centroidal
axes of the ferrules or are in the same quadrant.
Another popular optical fiber connector is one known as the SC
connector. An SC connector includes a ferrule assembly which
includes a barrel having a collar at one end and an optical fiber
terminating ferrule projecting from the barrel. The ferrule
assembly is disposed in a plug frame such that an end portion of
the ferrule 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. The plug frame is
configured so that it is polarized with respect to a grip into
which the plug frame snap-locks. One grip is inserted into one end
of a coupler housing and another grip is inserted into another end
of the coupler housing to cause the ends of the ferrules to become
disposed in optical connection with each other.
The foregoing assembly is made so that the direction of
eccentricity of the ferrule passageway becomes aligned with a key
disposed on an outer surface of the grip. In order to cause the
direction of eccentricity to become aligned with the key, inasmuch
as the plug frame can only be inserted in one orientation, the
ferrule must be oriented with respect to the plug frame prior to
its assembly therewith. This is a somewhat difficult task and
consumes excessive time. Also, whereas the SC connector has a
number of advantageous features, in its present form it is
difficult to use to field-terminate optical fibers.
What is sought after and what seemingly is not available in the art
is an SC ferrule connector in which the eccentricity of the ferrule
fiber-receiving passageway is aligned with a key of a grip and in
which the eccentricity of the passageway may be determined after
the ferrule assembly has been assembled with another portion of the
connector and/or after the ferrule assembly has been used to
terminate an end portion of an optical fiber. The capability of
delayed eccentricity determination should reduce the cost of such a
connector and render it more marketable to a wider segment of the
industry. Also, sought after is an SC connector which is easily
used for field termination of optical fiber.
SUMMARY OF THE INVENTION
The foregoing problems of the prior art have been overcome by the
connector of this invention. An optical fiber connector comprises a
ferrule assembly including a ferrule portion having a passageway
for an optical fiber, and a plug frame in which is disposed the
ferrule assembly. In a preferred embodiment, the plug frame
includes inwardly radially projection, circumferentially spaced
splines. The ferrule assembly is disposed in the plug frame such
that grooves formed between segmented portions of said collar
receive splines of the plug frame therebetween to prevent relative
rotation between the ferrule assembly and the plug frame. The
ferrule assembly includes a barrel portion which projects toward a
latching end portion of the plug frame. A ferrule projects toward
an opposite end portion of the plug frame which is destined to
become disposed adjacent to the corresponding end of a plug frame
of another connector. The opposite end portion of the plug frame is
symmetrical with respect to a transverse cross section. Spring
means is disposed about the portion of the ferrule assembly which
projects toward the latching end portion of the plug frame. The
connector also includes a cable retention member which includes a
pocket for the spring and the barrel portion. The cable retention
member effectively preloads the spring. The cable retention member
includes outwardly projecting tabs each of which is received in a
slot in the latching end portion of the plug frame to secure the
cable retention member to the plug frame.
Because of the symmetry of the opposite end portion of the plug
frame, the plug frame may be in any rotational orientation with
respect to another portion of the connector, which is called a
grip, when the two are assembled together. As a result, the ferrule
assembly may be assembled with the plug frame after which the
eccentricity of the optical fiber core or ferrule passageway may be
determined with an appropriate marking made on the plug frame. Then
the plug frame is assembled with the grip in such a way as to align
the direction of eccentricity with a key of the grip. But for the
symmetry, the direction of eccentricity would have to be determined
first and the ferrule assembly assembled with the plug frame in a
particular manner so that when the plug frame was assembled in the
only possible orientation with the grip, the direction of
eccentricity would be aligned with the key of the grip.
BRIEF DESCRIPTION OF THE DRAWING
Other features of the present invention will be more readily
understood from the following detailed description of specific
embodiments thereof when read in conjunction with the accompanying
drawings, in which:
FIG. 1 is a partially exploded perspective view of a ferrule
connector of this invention;
FIG. 2 is an exploded perspective view of portions of the connector
of FIG. 1;
FIG. 3 is a side elevational view partially in section which shows
the connector of FIG. 1 in an assembled state;
FIG. 4 is an elevational view of the assembled connector rotated
90.degree. to the view of FIG. 3 to show a key of a grip in which
portions of the connector are received;
FIG. 5 is a side elevational view partially in section of a
connector of this invention which is used to terminate a buffered
optical fiber;
FIG. 6 is a side elevational view partially in section of a prior
art connector;
FIG. 7 is an exploded perspective view of the optical fiber
connector of FIG. 1 and a coupling housing in which the optical
fiber connector and another identical optical fiber connector are
to be disposed;
FIG. 8 is an end view in section of the assembled connector of FIG.
3 showing portions of the grip latched into grooves of a plug frame
to secure together portions of the connector; and
FIG. 9 is an end view of the assembled connector of FIG. 8 with
forces being applied to diagonally opposed corners thereof to cause
disengagement of the latching portions of the grip with the plug
frame.
DETAILED DESCRIPTION
Referring now to FIG. 1, there is shown a connector which is
designated generally by the numeral 20 which is adapted to
terminate an optical fiber cable 21. The connector 20 comprises a
ferrule assembly which is designated generally by the numeral 22.
The ferrule assembly includes a barrel 24 (see also FIG. 2) having
a segmented collar 26 at one end thereof. For the purpose of
antirotation the collar 26 is provided with segments 28--28 with a
groove 29 formed between each adjacent two of the segments. Four
segments 28--28 are preferred but more or less could be used.
Extending from a cavity in an opposite side of the collar 26 is a
ferrule 30 which is made of a ceramic material, for example, and
which has an optical fiber receiving passageway 32 formed along a
longitudinal centerline axis thereof. Further, a free end of the
ferrule 30 has a beveled portion 34 which facilitates insertion of
the ferrule into an alignment device. In order to facilitate the
insertion of one end portion of an optical fiber 35 (see also FIGS.
3 and 4) of the cable 21 to be terminated by the ferrule, the
barrel includes a bore 36 which is aligned with the passageway in
the ferrule and an entrance 37 to the ferrule passageway is
funnel-shaped. For a buffered optical fiber, for example, the
buffer layer extends to the entrance 37.
Adapted to be assembled with the ferrule assembly 22 are a spring
38 and cable retention member 40 (see also FIGS. 2-4). The cable
retention member 40 is cylindrically shaped and includes a pocket
portion 42 adapted to receive the barrel 24 and the spring 38 of
the ferrule assembly. Projecting from an outer surface of the
pocket portion 42 are circumferentially disposed tabs 44--44 which
are useful for securing the cable retention member to another
portion of the connector to be described hereinafter. Also, the
cable retention member 40 includes a circumferential groove 45,
collars 46 and 48 and a strength member retention portion 49. The
strength member retention portion 49 is adapted to have strength
members 47--47 included in a sheath system of a single optical
fiber cable extend into engagement therewith.
Adapted to be assembled to the cable retention member 40 is a crimp
portion 50 which includes a stepped cylindrical sleeve 52 having a
small diameter portion 54 and a large diameter portion 56. The
sleeve 52 is adapted to be crimped about an end portion of a single
optical fiber cable to be terminated by the connector 20. A mandrel
58 includes a flange 59 and a tubular portion 61. An end portion of
the cable 21 to be terminated with the mandrel 58 already
preinserted is moved into the crimp portion 50 such that the
tubular portion 61 becomes disposed inside the sheath of the cable.
The flange 59 becomes disposed just outside the strength member
retention portion 49 or to the left thereof as viewed in FIG. 3.
After the optical fiber from the end portion of the cable has been
extended into the ferrule assembly such that an end of the fiber
extends from the ferrule, a craftsperson causes the sleeve portion
54 to be crimped about the cable and the sleeve portion 56 to be
crimped about the strength members of the cable from which the
jacket has been removed. The tubular portion 61 of the mandrel 58
acts as an anvil during the crimping action to prevent damage to
the optical fiber. Strength members 47--47 of the cable such as
aramid fiber strength members are disposed about the periphery of
the cable retention member and becomes gripped between the portions
56 and the cable retention member 49 as a result of the crimping
(see FIGS. 3 and 4).
Should the optical fiber cable be simply a buffered fiber 63 (see
FIG. 5) with no strength members, then the crimp potion 50 is
deemed unnecessary. In that arrangement, the optical fiber cable
extends into the barrel portion 24 and the fiber 35 into the
passageway 32.
The ferrule assembly 22, the spring 38, the cable retention member
40 and a plug frame which is designated generally by the numeral 70
are adapted to be assembled (see FIGS. 1 and 2) together in what
may be referred to as a cable or optical fiber terminator portion
of the connector. The cable or optical fiber terminator portion may
be factory preassembled. Factory assembly saves time and assembly
costs in the field.
The plug frame 70 may be made of a plastic material such as
polycarbonate and includes a forward end portion 72 which is formed
with four chamfers 74--74 one at each two intersecting surfaces
73--73. The forward end portion 72 which includes a cavity 75
having a circular cross section is integral with a rear end portion
76 which has a circular tubular configuration in a transverse
cross-section. The rear end portion 76 includes two diametrically
opposed longitudinally extending slots 78--78 and two
circumferentially extending windows 79--79. The rear end portion 76
includes a bore 77 (see FIG. 4) for receiving the ferrules and
which transitions through a tapered portion to the cavity 75. Each
of a plurality of splines 81--81 (see FIG. 3) project radially
inwardly from the inner surface of the plug frame. Projecting from
each outer surface 73 adjacent to the junction with the rear end
portion is a detent 91.
As should be apparent from FIG. 2, the forward end portion 72 of
the plug frame 70 is symmetrical in a cross section transverse of
the longitudinal axis of the plug frame. In the prior art
connector, the leading end was unsymmetrical.
When the ferrule assembly 22 is assembled to the plug frame 70, the
ferrule 30 is received in the forward end portion and the barrel 24
is received in the tubular end portion 76. Segmented portions of
the ferrule assembly become disposed between the internally
projecting splines 81--82. This prevents rotation of the ferrule
assembly 22 relative to the plug frame 70. Furthermore, when the
ferrule assembly and the cable retention member are assembled to
the plug frame, the tabs 44--44 radially projecting from the pocket
portion of the cable retention member snap-lock into the windows
79--79 of the plug frame to hold the cable retention member secured
to the plug frame.
Then the craftsperson tests the cable terminator portion comprising
the ferrule assembly 22, the spring 38, the plug frame 70 and the
cable retention portion 40 to determine the direction of any
eccentricity of the passageway 32 in the ferrule 30. After this has
been determined, the craftsperson provides a marking or otherwise
identifies such direction on the plug frame 70.
Then an end portion of a cable which is to be terminated by the
connector 20 is prepared. An outer jacket is removed from an end
portion to expose strength members 47--47 or to expose an optical
fiber. Provisions are included for holding the end portion of the
cable secured to the connector.
The connector 20 also is provided with a cable strain relief
portion 80 (see FIGS. 1-4). The cable strain relief portion 80
includes a portion 82 which is flexible and includes a large
diameter portion 83 and a small diameter portion 84 joined by a
tapered portion 86. Projecting from the large diameter portion 83
is a rigid portion 87 which includes a plurality of segments 88--88
each having a hook-like end portion 89.
During the assembly of the strain relief portion 80 with other
portions of the connector, the rigid portion 88 is moved over the
crimp portion 50. Movement of the strain relief portion 80 is
discontinued when the hook-like end portions 89--89 snap-lock into
the circumferential groove 45 in the cable retention member 40.
This arrangement also is a departure from the prior art. In the
prior art connector of FIG. 6, hook-like end portions of the rigid
portion of the cable strain relief portion latch behind an end
portion of the crimp portion 50 instead of in a groove of the cable
retention member. Because the cable retention member is secured to
the plug frame, the securing of the strain relief portion to the
cable retention member provides a more integral structure. Also,
advantageously the same elements of the connector 20 are used to
secure the cable retention member to the plug frame in those
instances when the transmission media structure being terminated
does not include strength members and the crimp portion is not
used.
As will be recalled, FIG. 5 depicts a connector of this invention
which is adapted to be used to terminate a buffered optical fiber
instead of a cable. For such an embodiment, the strain relief
portion 82 of FIGS. 3-4 is modified to have the configuration shown
in FIG. 5 and designated with the numeral 85.
Then the craftsperson assembles the terminated cable comprising the
cable 21, the strain relief portion 80, and the crimp portion 50
and the cable terminator with a grip which is designated generally
by the numeral 90 (see FIG. 1). The grip and the plug frame
assembly are configured so that the plug frame with the forward end
portion 72 may be in any of four rotational orientations with
respect to the grip and be assembled thereto. As will be recalled a
forward end portion of the plug frame is symmetrical in a cross
section normal to a longitudinal axis of the connector. The
assembly is made so that the marking on the plug frame 70 is
aligned with a key 92 projecting from an outer surface 94 of its
grip. In this way, the key 92 is indicative of the direction of
eccentricity of the plug passageway. By causing the direction of
eccentricity of the plug passageway of one ferrule assembly to be
in the same quadrant of another ferrule assembly to which it is
optically connected, losses are reduced substantially. Of course,
it should be understood that the direction of eccentricity could be
that of the core of the optical fiber in which situation, the
determination of eccentricity is made after the cable has been
terminated by the cable terminator portion of the connector 20.
Such an arrangement is advantageous over the prior art. In a prior
art SC connector (see FIG. 6), the terminated cable had to be in a
predetermined orientation with respect to the grip 90 to enable
assembly. Hence for the direction of eccentricity of the ferrule
passageway or of the optical fiber core to be aligned with the key
92, the ferrule assembly had to be assembled to the plug frame such
that the eccentricity was in a particular direction with respect to
the plug frame. This required that the direction of eccentricity be
determined prior to the assembly of the ferrule assembly to the
plug frame. With the arrangement of this invention, the ferrule
assembly is assembled to the plug frame after which the direction
of eccentricity of the plug passageway or fiber core is determined.
The direction of eccentricity can be determined before or after the
optical fiber is disposed in the ferrule passageway.
It also should be mentioned that the arrangement of the segmented
collar of the ferrule assembly 22 and the splines 81--81 can be
used to cause the quadrant of eccentricity of the optical fiber
core or passageway in the ferrule to be aligned with a particular
spline which cause it to have a known orientation with respect to
an outer portion of the plug frame.
As can be seen in the drawings, the grip 90 comprises an elongated
plastic housing 96 having one end 98 (see FIG. 1) into which the
plug frame assembly is inserted and an opposite end 99 which is
adapted to be inserted into a coupling housing 100 (see FIG. 7) in
order to facilitate an optical connection between two optical
fibers terminated by two ferrule assemblies. The assembly is made
to cause the key 92 of the grip to be received in a keyway 102 of
the housing 100. A free end portion of a ferrule 30 is received in
an alignment sleeve 105 (see FIG. 7). At its end 98, the housing 96
is formed with two locking nubs 101--101 formed in opposite
internal corners. Each locking nub 101 is adapted to snap-lock into
a groove 103 (see FIG. 2) along one of the chamfers 74--74 of the
plug frame (see FIG. 8). This secures the plug frame to the grip.
In order to disassemble the plug frame from the grip, a
craftsperson need only squeeze the grip at opposite corners thereof
(see FIG. 9). This causes the tabs to become disposed outside the
grooves of the plug frame and allows the plug frame assembly to be
withdrawn from the housing of the grip.
As can be seen in FIG. 7, the coupling housing 100 is formed with
two longitudinally aligned keyways 102--102. When two connectors
20--20 each including a grip are inserted into the housing with the
keys aligned axially, the connectors become connected such that the
quadrant direction of eccentricity of the ferrule passageways or
fiber cores are aligned.
The connector also has provisions for becoming secured to the
coupling housing 100. As will be recalled, each forward surface 73
of the plug frame 70 is formed with a detent 91 projecting
therefrom. As is seen in FIG. 7, the near end of the coupling
housing includes a depressible latching finger 106. A second
latching finger 106 extends from an opposite wall but is not seen
in FIG. 7. The far end of the coupling housing also is provided
with a pair of opposed latching fingers. A connector 20 is inserted
into the coupling housing until the latching fingers 106--106
associated with the end of the housing into which the connector is
inserted ride past beams 107--107 which define openings 108--108
and along sidewalls 109--109 and snap-lock behind opposed detents
91--91 of the plug frame. Because the plug frame is provided with
four such detents 91--91, the latching of the connector 20 to the
coupling housing 100 can occur notwithstanding which of four
orientations, 90.degree. to one another, the plug frame is in
relative to the coupling housing.
The configurations of the detents 91--91 and of the latching
fingers 106--106 are such that upon the application of forces of a
predetermined magnitude, typically on the order of about 2-4 lbs.
to the grip 90 in a direction toward the cable 21, the latching
fingers 106--106 are cammed up along the sidewalls 109--109 which
causes the latching fingers to be spread apart to facilitate
withdrawal of the connector 20 from the coupling housing 100.
Another feature of the connector 20 is shown in FIG. 7. The grip 90
is formed to include ports 110--110 which allow viewing of the plug
frame 70 which may be a different color than that of the grip.
During insertion of the grip 90 into a coupling housing 100, the
non-visibility of the ports is indicative of full insertion of the
grip into the coupling housing. This feature avoids the need to
provide a secondary marking on the grip, the non-visibility of such
serving the same function.
It is to be understood that the above-described arrangements are
simply illustrative of the invention. Other arrangements may be
devised by those skilled in the art which will embody the
principles of the invention and fall within the spirit and scope
thereof.
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