Note: Descriptions are shown in the official language in which they were submitted.
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OPTICAL FIBER CONNECTOR AND MEANS AND ~ETHOD
FOR CENTERING OPTICAL FI~ER
BACKGROUND OF THE PRIOR ART
This invention relates generally to fiber optic connectors
and, more speciflcally, to a separable in-line fiber optic connector
for coupling a palr of fiber optic cables or a single flber optlc
cabls and a light source or detecfor. The terminal end surface of
an Inner fiber core for use tn llghtwave transmlssion must be flat
and highly pollshed to minlmize Insertion losses. The Inner fiber
core typlcally must also be axlally, laterally, and angularly
allgned wlthln certaln parameters to establIsh an excellent opflcal
coupllng between two flber optlc cables. The success achleved In the
development and productlon of flber optlc cables has therefore
focused strongly upon low loss connectors and couplers for such
cables Includlng In-llne connectors. The abillty to deslgn, manu-
facture, deploy and servlce a data transmission llne, for Instance,
requlres suitable oonnectors in order to assure the continued
progress of the fiber optlcs field. Accordingly, connectors for
this and other applications must be developed which can be used
without any significant Increase In Insertion losses.
Many fiber optic connectors presently available are
preclsion, expensive instruments providing very low insertTon
losses but they are deslgned for certain applications such as
long dlstance applications in telephonic systems and in other
appllcatlons requlring extremely low insertion losses where expen-
sive low 105s connectors may be employed. It has been found, however,
thaf expenslve low loss connectors are not always well sulted for
applicatlons requlring a large number of connectors where very expen-
sive connectors are not economlcally feaslble. For Instance, In
such appllcatlons as computers and other data transmlssion appllca-
tlon, a large number of flber optlc cables are employed and there
Is a need for low cost, low loss fiber optlc connectors whlch
mlnimlzes Insertlon losses due to off-centerlng of the flber core
relative to the connector or terminal member. It is well known In
such appllcations to use low cost flber optlc cables In whlch the
Inner flber core ts often not concentrTc with the outer coatlng or
claddlng. Of course, thls non-concentrlcity has a tendency to lead
to excesslve Insertion losses when a connector that utllizes the
outer or claddlng as a Jlgging surface Is put Into a data transmission
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line.
As stated above, alignment of the fiber core is important
to mintmize insertion losses, but mest connectors which are effective
to properly position or center the core with respect to the mating
terminal end of the connector or terminal member are very expensive
instruments. Thls invention is dlrected to solving these problems
by providlng a new and improved fTber optic connector and means and
method of centering or properly positionlng optlcal flbers or Inner
ftber cores of fiber optic cables with respect to the matlng terminal
end of the connector.
BRIEF SUiMMARY Oi~ THE INVEiiTlON
Accordlngly, a princlpal obJect of the present inventlon
Is to provlde a new and Improved low cost, low loss, separable In-
llne flber optlc connector adapted for coupling a palr of flber opt1c
cables or a slngle flber optlc cable and a light source or detector.
Another obJect of the Invention is to provlde a flber optlc
connector whlch includes new and improved, sTmple and tnexpensive
means associated wlth the connector for properly poslttonlng or
centering an optlcal flber or fTber core of a fiber optic cable wlth
respect to the mating end of the connector.
A further obJect of the inventlon is to provide a means or
method of centering an optical fiber or fiber core of a fiber optic
cable In a fiber optlc connector.
In uslng optical f7bers, such as a plastTc clad silica flber,
the tnner fiber core or optical flber often is not concentrtc with the
outer diameter of the plastic claddlng or outer coatlng. This non-
concentricity leads to excessive Insertion losses when a connector Is
put Into a llne that utlllzes the outer dlameter of the claddlng or
coatlng as a Jlgglng means or surface. The present Invention provides
a flber optic connector for optical coupling of a pair of flber opttc
cables or a slngle flber optlc cable and a llght source or detector,
whereln the cable Includes an outer coatlng and an Inner flber core
whlch may or may not be concentrlc wlth the outer coatlng. The con-
nector of the present invention mitigates agalnst insertion losses by
assuring that the fiber core is aligned wlth respect ot the mating
end of the connector~ independently of the non-concentricity between
the core and the outer diameter of the coating or cladding.
More particularly, the fiber optic connector of the present
invention Includes a terminal member having a through hole extending
axially therethrough. The through hole has a first portion
extending through a forward extension of the terminal member.
The first portion of the through hole is sized to snugly receive
a length of the fiber core stripped of the outer coating to
properly position the core in a selected position in the terminal
member. The through hole includes a second portion rearwardly
of the first portion for receiving the outer coating. The second
portion is sized sufficiently larger than the outer coating of
the fiber optic cable to accommodate any eccentricity between
the fiber core and the outer coating. Means is provided for
fixedly securing the outer coating of the fiber optic cable within
the second portion of the through hole to maintain the core
properly positioned in the terminal member. The forward extension
is constructed so as to be readily removable from the remainder
of the terminal member to form a forward mating end with the
fiber core located in the selected position in the terminal
member.
In the exemplary embodiment disclosed herein, the first
portion of the through hole is formed in a reduced boss portion of
the terminal member and protrudes outwardly from a body portion
of the terminal member. The means for fixedly securing the outer
coating of the fiber optic cable within the second portion of the
through hole comprises an epoxy material. After the epoxy hardens,
the boss portion is removed from the body portion of the terminal
member, leaving the core properly positioned or centered in the
terminal member. Of course, more than one through hole may be
provided in a single terminal member body portion to accommodate
a plurality of fiber optic cables.
The invention is also directed toward a method of
locating an inner fiber core of a fiber optic cable in a selected
position in a fiber optic connector, wherein the inner fiber core
may or may not be concentric with an outer coating of fiber optic
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cable. The method comprises: providing the fiber optic con-
nector with means for locating the inner fiber core in the
selected position; locating a length of the inner fiber core,
stripped of the outer coating, in the selected position in the
fiber optic connector utilizing the locating means; securing a
portion of the outer coating to the fiber optic connector while
the inner fiber core is so located to thereby maintain the
inner fiber core in the selected position in the fiber optic
connector; and removing the locating means of the fiber optic
connector after the outer coating portion is secured to the fiber
optic connector.
The features of the present invention which are believed
to be novel are set forth with particularity in the appended claims.
The invention, together with the further objects and advantages
thereof, may best be understood by reference to the following
description taken in conjunction with the accompanying drawings.
In the drawings, like reference numerals identify like elements in
the several figures, in which:
FIGURE 1 shows a front perspective view of the fiber
optic connector of the present invention having a pair of fiber
optic cables terminated therein with the centering or positioning
boss removed;
FIGURE 2 is a vertical sectional view through the
fiber optic connector and one of the through holes thereof, with
the top portion of the connector removed;
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FIGURE 3 is an end elevatlonal view looking in the direction
of arrows 3-3 of Figure 2;
FIGURE 4 is a vertlcal sectional view slmilar to that of
Figure 2, with an inner fiber core of a fiber optic cable properly
posltioned so that a stripped portlon of the core extends through
the centering boss;
FIGURE 5 Is a vertlcal sectional view slmllar to that of
Flgure 4, with epoxy materlal surrounding an outar coatTng of the
flber optlc cable wlthTn the connector, with the top portlon of the
connector In proper posltion;
FIGURE 6 Is a vertlcal sectlonal vlew taken generally along
the llne 6-6 of Flgure 5;
FIGURE 7 Is a vertlcal sectlonal view slmilar to that of
Flgure S, wlth the centerlng boss and assoclated portlons of the
flber optlc cable removed, leadlng the Inner flber core properly
posltloned In the terminal member; and
FIGURE 8 7s an end elevational view looking generally In
the direction of arrows 8-8 in Figure 7.
DETAiLED Di--SCRlPTlC~i OF THE INVENTlOii
Referring to the drawings in greater detall, a separable
in-llne flber optlc connector is shown generally designated 10 In
Figure I which is designed to recelve and terminate a palr of fiber
optic cables 12. However, the connector may be designed to receive
and terminate a single flber optic cable or a plurality thereof more
than the two cables shown. i~eferring to Figures 4 and 5, the cable
12, prlor to assembly to the hole is disposed adjacent to or rearwardly
of the flrst portlon 26 for rec~lving the outer coated or cladded
portlon 16 of the fiber optlc cable 12. The second portlon 28 of the
through hole is overslzed or slzed sufficlently larger than the outer
coatlng 16 to accommodate any eccentrlcity between the flber core 14
and the outer diameter of the coating 16. The thlrd portlon 30 of
the through hole Is provlded to accommodate the remalntng, rearwardly
extendlng portlon of the flber optlc cable 12. Of course, It is
comtemplated that a through hole whlch would include only the first
and second portions 26 and 28, respectlvely, may be utlllzed for
centerlng purposes.
The assembly of the flber optic cable 12 within the respec-
tive portions 26, 28 and 30 of the through hole is best seen by first
referring to Figure 4. After thls step of assembly, means Is provided
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in the form of an epoxy material 32 for fixedly securing the outer
coating 16 within the second portion 28 of the through hole. The top
half 20 of the body portion of the terminal member 10 then Is placed
in position as shown in Figure 5. Upon hardening of the epoxy
material 32, the outer coating 16 will be fixedly secured In ptace
wlthin the connector to maintaln the fiber core 14 properly posi-
tioned or centered with respect to the forward matlng end of face 24
or the termTnal member 10. The top half 20 of the termlnal member
also will be fIxed in place about the coating 16 of cable 12.
The next step of the present invention is shown best in
Flgure 7 and comprises the procedure of removing the centertng boss
22 and assoclated flber core, or optlcal flber 14 and plastlc
claddlng, or outer coatlng of the flber optic cable 12 as shown by
the phantom llnes In Flgure 7. After the boss and cable portlons
are removed, as by shearlng, the flber optic connector 10, Is strlpped
so that a length of Its Inner fiber core 14 and a length of the
cladding or outer coatlng 16 about the core 14 are exposed, as shown,
In order to be properly received within the connector as described
In greater detail herelnafter. The connector 10 Includes a terminal
member or body portion which includes a lower half 18 and an upper
halfi 20.
Referring to Flgures 2 through 7, the body portlon of the
terminal member 10 InTtially is provided with a centering boss 22
molded Integrally with the forward or mating end 24 whlch Ts defined
by the forward end of the lower half 18 of the body portion of the
terminal member. The centering boss 22 is reduced in size and
protrudes outwardly or forwardly of the termlnal mating end 24. In
the examplary embodiment of the invention, a centerlng boss 22 Is
provlded for each flber optlc cable as best shown In the end eleva-
tlonal view of Figure 3, but it is contemplated that a slngle boss
may be provided for multlple flbers.
The termlnal member 10 Includes a through hole extendlng
axlally therethrough. The through hole Includes a first portlon 26
(see partlcularly Flgure 2), a second portion 28, and a thlrd portion
30. The first portion 26 of the through hole extends through the
centering boss 22 and is slzed to snuggly receive the length of the
fiber core 14 stripped of the outer coattng 16 of the fiber optic
cable 12 to properly position the core with respect to the forward
mating end or face 24 of the terminal member 10. The second portion
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28 of the through hole is disposed adjacent to or rearwardly of the
first portion 26 for receiving the outer coated or cladded portion
16 of the fiber optic cable 12. The second portion 28 of the through
hole is oversized or sized sufficiently larger than the outer coatlng
16 to accommodate any eccentricity between the fiber core 14 and the
outer diameter of the coating 16. The thTrd portion 30 of the through
hole is provided to accommodate the remaining, rearwardly extending
portion of the fiber optlc cable 12. Of course, It is contemplated
that a through hole which would Include only the first and second
portions 26 and 289 respectively, may be utilized for centering
purposes.
The assembly of the flber optic cable 12 withi,l the
respective portions 26, 28 and 30 of the through hole Is best seen
by first referring to Flgure 4. After this step of assembly, means
is provided in the form of an epoxy material 32 for fixedly securlng
the outer coating 16 within the second portion of the terminal member
10 then is placed In posltion as shown in Figure 5. Upon hardening
of the epoxy material 32, the outer coating 16 will be fixedly secured
In place within the connector to maintain the fiber core 14 properly
positioned or centered with respect to the forward mating end or
face 24 or the terminal member 10. The top half 20 of the terminal
member also wlll be fixed in place about the coating 16 of cable 12.
The next step of the present invention is shown best In
Figure 7 and comprises the procedure of removing the centering boss
22 and associated fiber core or optical fiber and plastic cladding or
outer coating 16 of the flber optic cable 12 as shown by the phantom
llnes in Figure 7. After the boss and cable portions are removed, as
by shearing, the fiber optlc cable 12 Is properly posltioned In the
termlnal member 10 wlth the core 14 properly centered wlth respect to
the matlng end or face 24, as shown In Flgure 6, not wlthstanding any
eccentricity between the core 14 and the outer dlameter of the outer
coating 16. The end of the terminal member 10 then can be properly
pollshed for In-line coupling of a pair of flber optic cables or a
slngle flber optic cable and a light source or detector.
It is readily apparent from the above descrlption of the
present invention, including the overall fiber optlc connector structure
as well as the means and method of centering optical fibers, that the
centerlng of the flber core 14 with respect to the mating end of the
termlnal member 10 is not dependent upon the precise positioning of a
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Jigging surface such as the inner diameter of the through hole
portion 28 as is prevalent in many fiber optic connectors presently
available. In addition other extraneous jigging means as Is pre-
valent in many expensive optical fiber connectors or l;instrumentsi
Is ellminated. Thus with the present invention it is contemplated
to provlde a fiber optic connector and centering means wherein a
termlnal member slmply Includes first means for receiving the length
of the flber core 14 stripped of its outer coating 16 to properly
posltion or center the core with respect to the mating end of the
termlnal member and second means for recelving the adjacent outer
coated portion 16 of the flber optic cable 12. Further means for
flxedly securlng the outer coated portlon 16 In the second means to
maintaln the flber core 14 properly posltioned wlth respect to the
matlng end of the termlnal member 10 Irrespectlve of any eccentrlclty
between the f1ber core 14 and the outer coated portion 16 Is provlded.
Epoxy materlal 32 has been shown as one form of provldlng the securlng
means~
Whlle in the foregoing specification a detailed descrlptlon
of the Inventlon has been set forth for purposes of illustration
variation of the details herein glven may be made by those skllled
in tha art without departing from the spirit and scope of this
invention.
