Connector for fiber optic member

A connector for a fiber optic member comprises a ferrule in which is positioned an insert surrounding a section of the fiber optic member adjacent an exposed end of the fiber optic member, the exposed end extending along a front bore of the ferrule. A crimping ring on the ferrule is controllably crimped thereon thereby moving arcuate sections of the insert into mechanical engagement with the fiber optic member with no or minimum deformation to the fiber optic member and securing the fiber optic member in the ferrule. A single crimping ferrule can be used if desired.

FIELD OF THE INVENTION 
This invention relates to a connector for a fiber optic member and includes 
an insert surrounding buffer material adjacent an exposed end of the fiber 
optic member and is positioned within a ferrule opening with arcuate 
sections of the insert being moved into engagement with the buffer 
material when a crimping ring on the ferrule is crimped thereon. 
BACKGROUND OF THE INVENTION 
U.S. Pat. No. 3,999,837 discloses a connector for a fiber optic member 
which includes a ferrule in which the fiber optic member and protective 
jacket thereon is disposed with an exposed end of the fiber optic member 
extending along a front bore. Potting material is applied onto the exposed 
fiber optic member before or after the fiber optic member is inserted into 
the ferrule. The potting material begins to cure thereby partly retaining 
the fiber optic member in the ferrule while the crimping ring is crimped 
onto the ferrule which holds the parts in place while the potting material 
fully cures. 
The use of potting material secures the fiber optic member in the ferrule, 
but it is messy, it is an extra step, and it takes time the cure. This is 
undesirable when terminations of fiber optic members need to be done at 
remote locations in the field and they need to be done quickly and easily. 
According to the present invention, a connector for a fiber optic member 
comprises a ferrule in which is positioned an insert surrounding a section 
of the fiber optic member adjacent an exposed end of the fiber optic 
member, the exposed end extending along a foot bore of the ferrule. A 
crimping ring on the ferrule is controllably crimped thereon thereby 
moving arcuate sections of the insert into mechanical engagement with the 
fiber optic member with no or minimum deformation to the fiber optic 
member and securing the fiber optic member in the ferrule. 
According to another aspect of the present invention, the fiber optic 
member with buffer material thereover can be encased in an inner jacket 
having woven fibers covering the inner jacket and an outer jacket 
thereover which constitutes a fiber optic cable for use in 
telecommunications. An outer crimping member is then used to crimp the 
woven fibers onto the ferrule adjacent the crimping ring and to crimp onto 
the outer jacket to terminate the fiber optic cable for joining ends of 
such cable together or for connecting the cable to a light-transmitting or 
sensing member. 
According to a further aspect of the present invention, a method of 
applying a connector to an end of a fiber optic member comprises the steps 
of placing an insert having arcuate sections onto the fiber optic member, 
inserting this assembly into a ferrule and controllably crimping a 
crimping ring on the ferrule thereby moving the arcuate sections into 
engagement with the fiber optic member thereby securing the fiber optic 
member to the ferrule.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIGS. 1 through 3 illustrate a connector C for terminating a fiber optic 
cable FOC. The fiber optic cable FOC includes a fiber optic member 10 
which includes a core or light-transmitting member surrounded by cladding 
material to enable light to be transmitted therealong. Buffer material 12 
covers fiber optic member 10 and is typically in the form of a plastic 
material to protect the fiber optic member. An inner jacket 14 also of 
plastic material surrounds buffer material 12 and lends strength to the 
cable to prevent the core or light-transmitting member from being broken 
since it can be made from glass or plastic material. Woven fibers 16 of 
plastic material surround inner jacket 14 to lend further strength to the 
cable and provides tensile strength thereto. An outer jacket 18 protects 
the entire cable assembly. The fiber optic cable FOC is stripped as 
illustrated in FIG. 2 to expose a length of woven fiber 16, buffer 
material 12, and fiber optic member 10 to enable the stripped fiber optic 
cable to be terminated onto connector C. 
Connector C includes a ferrule member 20, a metal crimping ring 22, an 
insert 24, a crimping ferrule 26 on which is captured a threaded nut 28. 
Ferrule 20 is made from a suitable plastic material having resilient 
characteristics and preferably fabricated by molding. It has a front 
cylindrical section 30, a central cylindrical section 32, and a rear 
cylindrical section 34, each of the cylindrical sections having a 
different diameter as can be discerned. A conical section 36 extends 
between sections 30 and 32. A rear bore 38 extends through sections 32 and 
34. A front bore 40 extends through front cylindrical section 30 and has a 
diameter to receive fiber optic member 10 therethrough, whereas rear bore 
38 has a diameter to receive insert 24 therein. Conical section 36 has an 
internal conical surface 42 extending between bores 38 and 40. 
Insert 24 is molded from a suitable plastic material and includes a conical 
section 44 and a cylindrical section 46. A bore 48 extends through insert 
24 to accommodate buffer material 12 of the fiber optic cable FOC. Slots 
50 are located in cylindrical section 46 at 120.degree. intervals 
therearound and they communicate with bore 48 thereby forming cylindrical 
section 46 into arcuate-engaging members. Slots 50 can be at right angles 
thereby forming four arcuate-engaging members. More slots can be provided 
thereby forming more than four arcuate-engaging members. 
To terminate fiber optic cable FOC by a connector C, the fiber optic cable 
is stripped as illustrated in FIG. 2 to expose woven fibers 16, buffer 
material 12, and fiber optic member 10. A beveled surface 52 is located in 
cylindrical section 46 at the entrance to bore 48 to facilitate the 
positioning of buffer material 12 within bore 48 of insert 24 until buffer 
material extends slightly outward from conical section 44 and fiber optic 
member 10 also extends outwardly therefrom as shown in FIG. 2. With 
crimping ferrule 26 and threaded nut 28 thereon positioned on the stripped 
fiber optic cable FOC, insert 24 with the bared buffer material 12 and 
fiber optic member 10 exposed in position therein is moved along rear bore 
38 in ferrule 20 until conical section 44 engages conical surface 42 and 
fiber optic member 10 extends outwardly from the front end of cylindrical 
section 30. Crimping ring 22 is then reduced in diameter by a crimping 
tool (not shown) thereby causing reduction of cylindrical section 34 under 
crimping ring 22 and the movement of the arcuate sections of cylindrical 
section 46 into engagement with buffer material 12 thereby securing buffer 
material and fiber optic member 10 in position in ferrule 20. If the light 
transmission member of the fiber optic member is glass, it is scribed and 
broken at the front surface of section 30. This causes the end of fiber 
optic member 10 to extend slightly beyond the surface of section 30. 
Ferrule 20 is rotated 90.degree. and crimping ring 22 is crimped again by 
the crimping tool which forms crimping ring 22 into a circular 
configuration which subjects ferrule 20 to a slight elongation which moves 
the front surface of section 30 into coincidence with the scribed and 
broken surface of the fiber optic member 10. 
Woven fibers 16 are then positioned along cylindrical section 34 as 
illustrated in FIG. 2 whereafter crimping the ferrule with threaded nut 28 
thereon is moved along woven fibers 16 and cylindrical section 34 until 
crimping ferrule 26 engages cylindrical section 32. The crimping ferrule 
26 engages cylindrical section 32. The crimping tool then reduces crimping 
ferrule 26 in the area overlying woven fibers 16 which also reduces 
cylindrical section 34 and moves other areas of the arcuate sections of 
cylindrical section 46 into engagement with buffer material 12 thereby 
providing an additional crimping area by ferrule member 20 with insert 
member 24 and insert 24 with buffer material 12, which results in a 
redundant crimping. The securing of woven fibers 16 between crimping 
ferrule 26 and ferrule 20 provides strain relief. Crimping ferrule 26 is 
lastly reduced in diameter along an area overlying fiber optic cable FOC 
thereby completely securing crimping ferrule in position and providing 
strain relief to the termination. 
If the light transmission member of fiber optic member 10 is formed of 
plastic material, the fiber optic member 10 extending beyond cylindrical 
section 30 after crimping ring 22 has been crimped in one direction it is 
subjected to a hot knife cut in accordance with conventional practice 
thereby providing a surface at right angles to the axis of fiber optic 
member 10. After fiber optic member 10 has been cut by the hot knife, 
fiber optic member 10 extends very slightly beyond the front surface of 
cylindrical section 30. Ferrule 20 is then rotated 90.degree. and crimping 
ring 22 is crimped by the crimping tool again to form crimping ring 22 
into a circular configuration which subjects ferrule 20 to a slight 
elongation which moves the front surface of cylindrical section 30 into 
coincidence with the cut surface of fiber optic member 10. Thereafter 
crimping ferrule 26 is moved into position along strength member 16 and 
cylindrical section 34 and crimping ferrule 26 is crimped at its two 
locations along ferrule member 20 and outer jacket 18 of the fiber optic 
cable FOC thereby securing connector C in position on fiber optic cable 
FOC thereby resulting in a proper and complete termination of the fiber 
optic cable. 
After ends of the fiber optic cable have been terminated by connector C, 
the connectors can be secured onto a coupling bushing 54 as shown in FIG. 
4. The bore of coupling bushing 54 has identical conical bores 58 leading 
to a central cylindrical surface 60. When threaded nuts 28 of connector C 
threadably engage coupling bushing 54, surface 58 engages conical section 
36 of ferrules 20 to radially compress these sections of the ferrules 20 
thereby causing resilient radial deformation thereof which biases the 
fiber optic member to a stable position within central cylindrical surface 
60 which will align fiber optic members 10 therein. The radial compression 
of two similar resilient ferrules within a commonly shaped surface 60 will 
bias corresponding light-transmitting members or cores 10 into coincident 
alignment even though the cladding layers over the light transmission 
members or cores are of different diameter. 
FIG. 5 shows a fixture 62 that is to be mounted onto a printed circuit 
board and a light-transmitting or light-sensing member (not shown) can be 
mounted within cavity 64. Connector C of a terminated fiber optic cable is 
then threadably secured onto fixture 62 which has a bore 60 and conical 
bore 58 of the same configuration as coupling bushing 54 to properly align 
the fiber optic member of the fiber cable with the light-transmitting or 
light-sensing member positioned in cavity 64. Connector C can also be 
connected to the optic adapter junction disclosed in U.S. Pat. No. 
4,186,996 as illustrated in FIGS. 5 and 6 thereof. 
As an alternative as shown in FIG. 6, crimping ferrule 26 can be used as a 
single crimping member which is first controllably crimped onto 
cylindrical section 32 thereby moving forward areas of the arcuate 
sections of insert 24 into engagement with buffer material 12; then 
crimping ferrule 26 is controllably crimped onto fibers 16 and section 32 
thereby moving rear areas of arcuate sections of insert 24 into engagement 
with buffer material 12 and finally crimping ferrule 26 is controllably 
crimped onto outer jacket 18 of the cable FOC. When the final crimping 
operation has been performed, the fiber optic member 10 is scribed and 
broken or hot knife cut at the front surface of section 30, whereafter 
ferrule 26 is rotated 90.degree. and controllably crimped again at the 
first crimped location thereby causing ferrule 20 to slightly elongate and 
move the front surface of section 30 coincident with the scribed and 
broken or cut surface of the fiber optic member.