U.S. patent application number 09/833321 was filed with the patent office on 2002-10-17 for alignment assembly for multi-optical fiber ferrules.
Invention is credited to Shahid, Muhammed A..
Application Number | 20020150349 09/833321 |
Document ID | / |
Family ID | 25264086 |
Filed Date | 2002-10-17 |
United States Patent
Application |
20020150349 |
Kind Code |
A1 |
Shahid, Muhammed A. |
October 17, 2002 |
Alignment assembly for multi-optical fiber ferrules
Abstract
A support member for forming connector ferrules by stacking two
or more support members together has first and second
longitudinally extending truncated V-grooves extending from the
face of the support member. The rear portion has at least one stop
member extending transversally from the wall of the groove and
defining a restricted passageway in the V-groove. An alignment pin
having a cylindrical shape has a reduced diameter groove near the
rear portion thereof which has a diameter slightly less than the
transverse dimensions of the restricted passageway and forming
front and rear shoulders, spaced a distance slightly greater than
the length of the stop members. The rear portion of the pin has a
pair of diametrically opposed flats whose transverse spacing
approximates the diameter of the reduced diameter groove.
Inventors: |
Shahid, Muhammed A.;
(Snellville, GA) |
Correspondence
Address: |
Daniel J. Santos, Esq.,
Thomas, Kayden, Horstemeyer & Risley, L.L.P.
Suite 1750
100 Galleria Parkway
Atlanta
GA
30339
US
|
Family ID: |
25264086 |
Appl. No.: |
09/833321 |
Filed: |
April 12, 2001 |
Current U.S.
Class: |
385/65 |
Current CPC
Class: |
G02B 6/3885 20130101;
G02B 6/3839 20130101; G02B 6/3878 20130101; G02B 6/3883
20130101 |
Class at
Publication: |
385/65 |
International
Class: |
G02B 006/38 |
Claims
1. An optical fiber connector ferrule comprising two or more
support members stacked together in mating relationship; each of
said support members having a face and having first and second
longitudinally extending spaced V-grooves therein extending
rearwardly from said face for forming an alignment pin passageway
when mated with a second support member; a first stop member
extending from the wall of at least one of said V-grooves defining
a restricted passageway in said ferrule having a transverse
dimension and a first length; an alignment pin having a transverse
dimension less than that of said alignment pin passageway and
greater than that of said restricted passageway and having a
grooved portion of a transverse dimension less than that of said
restricted passageway, the length of said grooved portion being
greater than that of said restricted passageway; and at least one
flat portion on said pin adjacent said groove and extending to the
rear thereof for creating a reduced transverse dimension of said
pin less than the transverse dimension of said restricted
passageway.
2. An optical fiber connector ferrule as claimed in claim 1 wherein
a second stop member extends from a wall of said V-groove opposite
and toward said first stop member to define said restricted
passage.
3. An optical fiber connector ferrule as claimed in claim 2 wherein
said grooved portion of said pin forms front and rear shoulders
which are adapted to bear against said stop member.
4. An optical fiber connector ferrule as claimed in claim 1 wherein
said alignment pin is cylindrical and said grooved portion has a
diameter less than the diameter of said pin.
5. An optical fiber connector ferrule as claimed in claim 4 wherein
said alignment pin has a rear portion extending from said grooved
portion, said rear portion having said at least one flat thereon
and a second flat thereon diametrically opposite said one flat, the
distance between said flats being less than the transverse
dimension of said restricted passage.
6. An optical fiber connector ferrule as claimed in claim 1 wherein
said alignment pin passageway extends from said restricted
passageway to a rear end of said passageway remote from said face,
forming a chamber within said ferrule.
7. An optical fiber connector ferrule as claimed in claim 6 wherein
said chamber communicates with the exterior of said ferrule through
a bore in said support member.
8. An optical fiber connector ferrule as claimed in claim 7 and
further including a resilient member within said chamber and
adapted to bear against the end of said alignment pin.
9. An alignment pin for use in an optical fiber ferrule, said
alignment pin comprising: an elongated cylindrical member having a
first end and a second end and a first diameter; a reduced diameter
groove in said cylindrical member intermediate said ends, said
groove being substantially closer to said second end than said
first end, the space between said reduced diameter groove and said
second end constituting a rear portion of said pin; and said rear
portion having a first flat surface thereon extending from said
groove to said second end.
10. An alignment pin as claimed in claim 9 and further having a
second flat surface on said rear portion diametrically opposite
said first flat.
11. An alignment pin as claimed in claim 9 wherein said pin is made
of metal.
12. An alignment pin as claimed in claim 9 wherein said pin is made
of a ceramic material.
13. A stackable optical fiber support member for forming a
connector ferrule, said support member comprising: a body member
having a front face and a rear portion; said body member having an
array of parallel V-grooves for containing optical fibers; an
enlarged V-groove on either side of said array and extending
substantially parallel to the grooves in said array from said front
face into said rear portion; and at least one stop member extending
transversely from a first wall of said enlarged V-groove to form a
restricted passageway therein.
14. A stackable fiber support member as claimed in claim 13 wherein
a second stop member extends transversely from a second wall of
said enlarged V-groove toward said at least one stop member and
spaced therefrom.
15. A stackable fiber support member as claimed in claim 13 wherein
said enlarged V-groove has a chamber formed therein extending from
said restricted passageway toward the rear of said support
member.
16. A stackable fiber support member as claimed in claim 15 wherein
said chamber has a passageway extending therefrom to the external
portion of said support member.
17. A stackable fiber support member as claimed in claim 13 and
having a first surface thereon; a locating lug extending from said
surface; and a locating slot for receiving a locating lug in said
surface and transversely spaced from said locating lug.
18. A stackable fiber support member as claimed in claim 13 wherein
said member is made of injection molded plastic material.
Description
RELATED APPLICATION
[0001] The subject matter of the present invention is related to
the subject matter of U.S. patent application Ser. No. 09/262,112
filed Mar. 4, 1999 of Shahid (Shahid 39) and patent application
Ser. No. 09/276,285 filed Mar. 25, 1999 of Shahid (Shahid 41), the
disclosures of both of which are incorporated by reference
herein.
FIELD OF THE INVENTION
[0002] This invention relates to optical fiber connectors and, more
particularly, to an alignment assembly for precision connection of
connector ferrules.
BACKGROUND OF THE INVENTION
[0003] Communication by means of optical signals transmitted over
optical fibers has become extremely popular and has given rise to a
unique and rapidly growing technology. In particular, optical
technology is being used more and more in broadband systems where
communication is by means of high speed optical channels. The need
for efficient utilization of available real estate on circuit
boards, racks and shelves, back planes, and distribution channels,
etc. is becoming increasingly important as miniaturization proceeds
apace, wherein generating, transporting, managing, and delivering
broadband service is performed in or by smaller and smaller
components. As a consequence, the industry has placed an emphasis
on small form factor optical connectors, such as the LC connector
from Lucent Technologies Inc. However, miniaturization is tempered
by the requirements of transmission efficiency. For instance, with
the advent of new standards such as Gigabit Ethernet, wherein the
transmission efficiency is becoming more and more critical, the
performance of optical connectors is becoming correspondingly
important for healthy operation of networks and systems. Thus, it
is desirable to obtain component miniaturization without
sacrificing transmission efficiency, and preferably while improving
transmission efficiency.
[0004] With the miniaturization of optical modules and optical
fiber devices, the management of optical fiber congestion has
become an issue at optical interfaces and connection distribution
points. One solution is the use of multi-fiber ribbon in which a
plurality of optical fibers are organized and molded side by side
in a plastic ribbon. It is known to interconnect these ribbon
cables by supporting the fibers between two support members
preferably but not necessarily made of a monocrystelline material,
such as silicon. In the support members are V-grooves formed
utilizing photolithographic masking and etching techniques. The
fibers are placed side by side in individual V-grooves of one
support member and the other mating support member having
corresponding V-grooves is placed over the fibers so as to bind or
hold the fibers in a high precision, spatial relationship between
the mating V-grooves. The top and bottom support members
sandwiching the multi-fiber ribbon are typically bonded together
with a clamp or adhesive, forming a ferrule of a multi-fiber
connector. Two mating ferrules with the same fiber spacing may then
be placed in an abutting relationship so that the ends of the
fibers of the respective ferrules are substantially co-axially
aligned with one another, thereby forming a multi-fiber connection.
If desired, such ferrules can be stacked in order to increase the
interconnection density.
[0005] Multi-fiber ribbons and connectors have numerous
applications in optic communication systems. For instance, some
opto-electronic and optical application specific integrated
circuits (OASIC) devices, e.g., optical switches, optical power
splitters/combiners, routers, etc. have several input and/or output
ports arranged as linear arrays to which a plurality of fibers are
to be coupled. Further, since optical fibers are attached to launch
optical signals into these devices and extract optical signals out
of these devices, splicing of arrays of fibers (i.e., a multi-fiber
ribbon) to such devices can be achieved using multifiber
connectors. Yet another possible application relates to an optical
fan-out fabric where an array of fibers in a multi-fiber ribbon may
be broken into simplex or duplex channels for distribution
purposes, as is often desired.
[0006] A critical factor to the optical efficiency of a multi-fiber
connector, whether or not stacked, is the precise alignment of the
mating ferrules with regard to one another. As the ferrule
structures utilized to achieve the precise axial alignment of
corresponding optical fibers of a multi-fiber connection become
smaller, there exists a need for connectors that are likewise space
efficient so that fill advantage of the miniaturized ferrule can be
realized with higher interconnection density. Further, there also
exists the need for multi-fiber connectors to be user friendly so
that the operation and utility of the multi-fiber connector is
intuitive to the workers that will be installing systems utilizing
optical components. For example, it is desirable for multi-fiber
connectors to have plug-and-play capability, in that they can be
quickly and easily coupled to a piece of equipment, device, or one
another. It is common practice in the art today to provide first
and second large V-grooves on either side of the array of V-grooves
in which the fibers are contained, and parallel thereto. The
enlarged V-grooves have mounted and affixed therein, as by
cementing, alignment pins which project out of the front face of
the ferrule. When a connection is to be made with another ferrule,
this other ferrule has the enlarged V-grooves but no alignment
pins, so that the alignment pins can fit therein in a male-female
connection, to align the two ferrules precisely and, hence, the
fibers contained therein. Such a connection is quickly and easily
accomplished, thereby fulfilling the user friendly desideratum.
[0007] Because of the high frequencies involved as well as the
large bandwidths of the signals being transmitted at high speed
through the connection, it is essential for optimum alignment of
the fibers that the faces of the ferrules be highly polished to a
high degree of flatness, and that they be clean or free of even
minute accumulations of dirt or dust. To this end, it is desirable
that cleaning the ferrules and, more particularly, their front or
butting faces, be done from time to time to insure optimum
cleanliness. However, because of the alignment pins projecting from
the front face, the cleaning and polishing of the ferrule faces is
extremely difficult to accomplish both from the standpoint of a
complete cleaning and polishing and from the necessity of
protecting the alignment pins from damage.
SUMMARY OF THE INVENTION
[0008] The present invention is directed to making the cleaning,
polishing, or re-finishing of a ferrule face from which the
alignment pin or pins project an easily performed operation.
[0009] In accordance with the principles of the invention, each of
the enlarged V-grooves in the support member for containing a
locating pin extends from the front face of the ferrule support
member toward the rear, parallel to the V-grooves for containing
the fibers. A rear portion of the enlarged groove has first and
second stop member projecting from opposite walls of the groove
forming a restricted space therein forming a chamber which extends
to the rear. Each chamber has a bore connecting it to the exterior
which is designated as an exhaust port. Thus when, for example, it
is desired, after the support members are assembled into a
sandwich, as discussed hereinbefore, to clean the enlarged
V-grooves, compressed air, for example, may be blown into the
passage formed by the enlarged V-grooves, and any dirt or debris is
exhausted out of the exhaust ports.
[0010] Alignment or guide pins for mounting in the enlarged
V-grooves are made of suitable hard, durable material, preferably,
but not limited to necessarily stainless steel, and each comprises
an elongated cylindrical member or rod having a chamfered front end
for ease of insertion into the enlarged V-groove of the mating
ferrule. The alignment pins may also be made of ceramic material.
The rear portion of the rod has a reduced diameter groove wherein
the diameter is only slightly less than the lateral spacing of the
stop members. Between the chamfered rear end of the rod and the
reduced diameter groove is a pair of diametrically opposed flats,
the distance between which is slightly less than the lateral
spacing of the stop members, being substantially equal to the
diameter of the groove. As will be seen hereinafter, the groove has
front and rear shoulders spaced apart a distance slightly greater
than the length of the stop members. These shoulders prevent the
alignment pin from moving axially, thereby functioning to hold the
pin in place within its groove. However, the flats eliminate the
rear shoulder so that if the pin is rotated to a position where the
flats are vertically oriented, the stop members no longer function
to prevent axial movement of the pin, and it may be introduced into
or withdrawn from the ferrule. With the pin withdrawn and separated
from the ferrule, the front face may easily be cleaned and
polished, after which the pin (or pins) is reinserted into its
V-groove opening in the ferrule, rotated so that the flats are
vertical so that the rear portion may be moved into the chamber,
and then rotated ninety degrees, for example, so that the front and
rear shoulders of the groove embrace the stop members to prevent
axial movement of the pin. The process is simply reversed to remove
the pin. Thus, the alignment pin need not be cemented in place and
can be removed and replaced as needed.
[0011] Various principles and features of the present invention
will be more readily apparent from the following detailed
description, read in conjunction with the accompanying
drawings.
DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 depicts a ferrule having a particular arrangement of
stackable support members;
[0013] FIG. 2 depicts a second ferrule made up of stackable support
members and having alignment pins;
[0014] FIG. 3 depicts a third ferrule made up of stackable support
members and having a polarizing arrangement of alignments.
[0015] FIG. 4 depicts the manner in which the stackable support
members are aligned;
[0016] FIG. 5 is a perspective view of the alignment pin of the
invention;
[0017] FIGS. 6 and 7 are side elevation views of the pin of FIG. 5,
axially rotated 90.degree. with respect to each other;
[0018] FIG. 8 is a rear elevation view of the alignment pin of the
invention;
[0019] FIG. 9 is a plan view of a support member with which the pin
of the invention is used;
[0020] FIG. 10 depicts the manner of inserting an alignment pin
into the support member;
[0021] FIG. 11 depicts a support member having two alignment pins
therein oriented in their operative position; and
[0022] FIG. 12 depicts a modification of the ferrule of FIGS. 10
and 11.
DETAILED DESCRIPTION
[0023] The present invention comprises a connector ferrule and
alignment pin for use in small form factor, multi-fiber connectors
for use, in turn, in high density interconnection systems and,
because of its unique structure, greatly simplifies the cleaning
and polishing of the ferrule, which is a necessity for optimum
operation of the connector.
[0024] In FIG. 1 there is shown a stackable ferrule 11 which
comprises two outer support members 12 which sandwich substantially
identical inner support members 13. The support members 12 and 13
are, as described in the aforementioned U.S. patent applications,
preferably made from injection molded plastic material as in the
aforementioned U.S. patent applications which is made to a high
degree of precision with a plurality of V-grooves 14 and 16 for
holding individual fibers in a parallel array within the ferrule.
The ferrule 11 of FIG. 1 terminates three multi-fiber ribbons, not
shown. On either side of the array, each of the members 12 and 13
has an enlarged terminated V-groove 17, 18 which, when the members
12 and 13 are stacked as shown in FIG. 1, form a passage 15,
parallel to the V-grooves 14 and 16, for holding alignment pins as
shown in FIGS. 2 and 3.
[0025] FIG. 2 Shows a ferrule 19 which comprises a stack of four
substantially identical support members 21 having four alignment
pins 22 projecting from the front face 23 of the ferrule thus
formed. Ferrule 19 is, therefore, a male ferrule adapted to mate
with a substantially identical female ferrule having the alignment
pin passages, but no alignment pins. The male-female relationship
of the ferrules is commonly used, however it necessitates that a
technician or installer carry both types. In FIG. 3 there is shown
a ferrule 23 which substantially the same as that shown in FIG. 2,
except that it only has two alignment pins 24 and 26 oriented on a
diagonal on the face 23 of the ferrule. It can be appreciated that
when the two identical ferrules to be joined face each other, the
pins 24 and 26 in each ferrule are directly opposite to, and
received by, empty passages in the other ferrule. Thus, connection
of the two ferrules can be made with only one orientation, and the
ferrules are said to be polarized. The stacking of the support
members must be done with precision so that each V-groove in each
support member is directly opposite the corresponding V-groove in
the contiguous support member. To this end and as shown in FIG. 4,
each support members has a locating lug 31 on one side of its top
(or bottom) surface, and a lug receiving hole 32 on the other side,
as shown in FIG. 6.
[0026] The ferrules depicted in FIGS. 1 through 4 are examples of
various ferrule configurations.
[0027] FIG. 5 is a perspective view of an alignment pin 31
embodying the principles of the present invention, and FIGS. 6, 7,
and 8 are detailed views thereof. As shown in these figures, pin 31
comprises a solid cylindrical body 32 having a front end 33 which
protrudes from the front face of a ferrule and a rear end 34. Body
32 is preferably made of a suitable metal, such as stainless steel,
although other materials having the necessary hardness, stiffness,
and durability might readily be used such as ceramic. As shown in
the figures, end 33 has a chamfer thereon to facilitate insertion
in the alignment passage of a mating ferrules, and end 34 likewise
is chamfered. In a region adjacent the rear end 34, body 32 has a
cylindrical groove 36 which forms a front shoulder 37 and a rear
shoulder 38. Body 32 extends for a short distance from rear
shoulder 38 to end 34, thereby defining a rear portion 39 which has
diametrically opposed flats 41 and 42 formed thereon. It can be
seen that the spacing between the flats 41 and 42 is substantially
equal to the diameter of groove 36, thereby eliminating two
segments of shoulder 38. While two flats are shown, a single flat
might be used provided it meets the criteria set forth
hereinafter.
[0028] In FIG. 9 there is shown a stackable support member 45 which
is configured to receive the alignment pin or pins 31 shown in
FIGS. 5 through 8. Support member 45 comprises a body 46 having a
front end or front face 47 and a rear end 48. Extending from front
face 47 toward the rear is a plurality of V-grooves 49 arrayed in
parallel for receiving and holding a corresponding plurality of
optical fibers, not shown. On opposite sides of the array of
grooves 49 is an enlarged truncated V-groove 51, 52 extending
parallel to the grooves 49 toward the rear of member 45. At the
inner or rear end portion of each of grooves 51, 52 is a pair of
protruding stop members 53, 54 spaced from each other as shown and
forming a restricted passageway. Extending from the rear 56 of the
stop members is a chamber 57 which communicates with the exterior
of member 45 by means of a bore 58. As pointed out in the
foregoing, bores 58 function as exhaust passages for chambers 57
during a cleaning operation, as with compressed air, when the
support members are arranged in a stack. Although two stop members
are shown, one stop member may possibly be used provided it meets
the criteria set forth hereinafter.
[0029] FIGS. 10 and 11 depicts the support member body 46 and
demonstrates the insertion of an alignment pin 31 therein (top pin
as viewed in FIG. 10) and an inserted pin 31 locked in place in
support member 46 (bottom pin as viewed in FIG. 10). As can be seen
in FIG. 10, the top pin 31 is rotated on its axis to where the
flats 41 and 42 can pass between stops 53 and 54 until shoulder 37
on pin 31 butts against the stops. Pin 31 is then rotated
approximately 90.degree. about its axis, as shown in the bottom pin
31 and in FIG. 11 so that shoulders 37 and 38 butt against both
sides of stop members 53 and 54, thereby preventing the pin 31 from
being pulled out of the pin 31. The axial length of cylindrical
groove 36 is preferably, although not necessarily such that both
shoulders 37 and 38 bear against the front and rear surfaces of the
stop members 53 and 54 so that the stop members are substantially
slip fits within the groove 36, thereby tending to hold alignment
pin 31 tightly. The pins 31 can be readily removed from the support
member body 46 by rotating them approximately 90.degree. on their
axes to permit flats 41 and 42 pass between the stops 53 and 54
whereupon the pins may be pulled from the support member 46 to
permit cleaning thereof, particularly of face 47.
[0030] FIG. 12 shows a modification of the arrangement of FIGS. 10
and 11 wherein a resilient member 61 is located within chamber 57
and applies an axial biasing force to pin 31 to insure that
shoulder 38 bears against the rear surfaces 56 of stop members 53
and 54. Member 61 is represented as a coil spring. However, because
of the very small dimensions involved, other suitable biasing means
such as a leaf spring or resilient material such as rubber, for
example, may better serve the purpose of applying a biasing force
to the rear end 34 of pin 31.
[0031] The ferrule and alignment pin combination of the present
invention, the embodiments shown, make possible the simple
insertion and removal of the alignment pins, thereby greatly
facilitating the cleaning, polishing, and/or renewal of the face of
the ferrule. It further relieves the installer or operator of
having to be equipped with separate male and female ferrules,
inasmuch as either may be realized through the addition or removal
of the alignment pins of the invention.
[0032] It is to be understood that the various features of the
present invention might be incorporated into other types of
connector arrangements, and that other modifications or adaptations
might occur to workers in the art. All such variations and
modifications are intended to be included herein as being within
the scope of the present invention as set forth in the forgoing.
Further, in the claims hereinafter, the corresponding structures,
materials, acts, and equivalents of all means or step-plus-function
elements are intended to include any structure, material, or acts
for performing the functions in combination with other elements as
specifically claimed.
* * * * *