Connector for an optical cable

Abstract: A connector (1') assembly with an optical cable (2) comprises, a shell (10') encircling a spring biased holder (13') for an optical fiber (3) of the cable (2), a sheath (16') to prevent leaking of adhesive from the holder (13'), and strength members (5) of the cable (2) anchored to the shell (10'). A sleeve (68) is secured to a coupling ring (18') and is reciprocatable and rotatable with the coupling ring (18').

Description: The invention relates to a connector for an optical fiber cable, and more particularly to an optical connector assembled to an optical fiber cable and supported by a sleeve. An optical cable is constructed with a central, buffer covered, optical fiber comprising an optical fiber for transmitting an optical signal, and a flexible buffer encircling the fiber and constructed of a solid polymeric material having a diameter many times larger than the diameter of the fiber. To resist a tensile force that might fracture the buffer covered fiber, the cable is constructed with a load bearing portion in the form of elongated strength members extending axially of the buffer covered fiber. The strength members extend between the sheath and the buffer covered fiber. EP-A-0 330 399 and US-A-4 812 009 which is equivalent thereto disclose a known connector for an optical cable comprising a plug connected to an optical fiber cable and extending through a cap to be secured to a coupling housing, and an extender secured to the cap and extending along the cable at a cable entrance end of the plug. Bending forces applied to the cable are transferred to the extender and to the cap. In the known connector, the extender locks the cap after the cap is secured to the coupling housing, and prevents rotation of the cap, necessary for uncoupling of the cap from the coupling housing. The extender is loosened with respect to the cap before the cap is permitted to couple or uncouple from the coupling housing. The present invention consists in a connector for an optical fiber cable, wherein the cable includes: at least one optical fiber having an outer layer of strength members, and wherein the connector includes: at least one elongate tubular holder which is for holding a corresponding optical fiber; a tubular shell which telescopically fits onto a rear end portion of the holder and is connectable to the strength members; and an outer coupling ring which fits over the shell and which has means for connection or disconnection with respect to a complementary connector, the connector being characterised in that the shell, the coupling ring and the holder are constructed so that the coupling ring is rotatable but is not reciprocatable with respect to the shell and is reciprocatable and rotatable with respect to the holder, and further characterised in that a sleeve secured to the rear of the coupling ring is reciprocatable and rotatable with the coupling ring during connection and disconnection to a complementary connector, and serves to transfer the bending forces from the cable to the coupling ring. Thus, the sleeve does not lock the coupling ring from movement, and is not required to be loosened or to be removed from the coupling ring. For a better understanding of the invention, reference will now be made, by way of example, to the accompanying drawings, in which: FIGURE 1 is a perspective view partially cut away of a further connector for optical fiber cable. FIGURE 2 is a section view of the connector shown in Figure 1. FIGURE 3 is an exploded section view of a portion of the connector shown in Figure 1. With reference to Figures 1 and 2, a connector 1′ for an optical fiber cable 2 includes a connector assembly 7′ which includes; a crimp ferrule 8′, a metal shell 10′ with a front shell portion 11′, a rear shell portion 12′, a holder 13′ for the optical fiber 3 comprised of a metal, plastic or ceramic alignment ferrule 14′ a metal body 15′, a sheath 16′ integral with the body 15′, a biasing spring 17′ of coil form, and a coupling ring 18′. The body 15′ includes an enlarged front end 19′ and a reduced external diameter intermediate portion 20′ intersection a rear facing shoulder 21′ of the front end 19′. The coil spring 17′ is assembled to encircle the reduced external diameter portion 20′ with a front end 23′ of the coil spring 17′ engaged and biased against the shoulder 21′. The body 15′ includes an axial passageway 24′ that has a reduced diameter, funnel entryway 25′ extending through an internal transverse web 26′, and enlarged diameter counter bore 27′ in the front end 19′. The ceramic alignment ferrule 14′ has a central longitudinal bore 28′ aligned with the entryway 25′. A rear end 29′ of the ferrule 14′ is press fit in the counterbore 27′ of the body 15′. The sheath 16′ is tubing shaped having a hollow interior 30′ formed by the passageway 24′, and a rear end portion 32′. The front end 19′ of the body 15′ provides a polarizing ring 9″ that includes a finger 34′ projecting transversely. The front shell portion 11′ includes a rear facing external shoulder 42′. The coupling ring 18′ has an enlarged diameter, front end 43′ and a reduced internal diameter opening 44′ extending through a transverse wall 45′. The coupling ring 18′ is assembled with the opening 44′ received slidably over the rear end 41′ of the front shell portion 11′. The front shell portion 11′ includes an axial cavity 46′ having a rear end 47′, an intermediate portion 48′ and a front portion 49′ extending through an end wall 50′ of the front body portion 11′. A hood 52′ extends forwardly from the front of the end wall 50′, and is shaped to provide a forward extending key. The key is slidably received in a longitudinal keyway 64 along the body 15′ to permit longitudinal movement of the body 15′ with respect to the shell 10′, but to prevent rotational movement of the body 15′ with respect to the shell 10′. The rear shell portion 12′ extends to a front facing external shoulder 55′ defined by an exterior spring clip 56′, and a rear facing external shoulder 57′ forwardly of a diameter end portion 58′ defining a cable anchoring portion. With reference to Figure 3, the holder 15′ and the biasing spring 17′ are assembled together and are assembled in the cavity 46′ of the front shell portion 11′, with the alignment ferrule 14′ projecting through the end wall 50′ forwardly of the end wall 50′, and with the sheath 16′ projecting outwardly of the rear end 58′ of the rear shell portion 12′. The rear shell portion 12′ is slidably assembled over the sheath 16′ of the body 10′. Then the end 32′ of the sheath 16′ is outwardly flared to limit forward movement of the sheath 16′ within an enlarged cavity portion 65 of the rear shell portion 12′. The biasing spring 17′ is in compression between the front end 53′ of the rear shell portion 12′ and the shoulder 21′ of the body 15′. Thereby the holder 13′ is biased forwardly by the spring 17′ and is mounted for axial slidable displacement and reciprocation with respect to the shell 10′. The keyway 64 and hood 52′ prevent rotation of the holder 13′ in the cavity 46′. The coupling ring 18′ is assembled over the shell 10′. The spring clip 56′ is assembled behind the coupling ring 18′. Thereby the connector assembly 7′ is fully assembled. With reference to Figures 1 and 2, a rear of the coupling ring 18′ includes external threads 66. An elongated sleeve 68 has an internally threaded front end 69 to be secured on the threads 66. The sleeve 68 extends rearward and has a hollow interior 70 to encircle the body 10′ and the crimp ring 8′. A rear end 71 of the sleeve 68 is to be secured to a strain relief boot 9′. Assembly of the connector 1′ to the cable 2 is described as follows. A quantity of a known, commercially available adhesive is deposited in the body 15′ of the holder 13′. For example: the adhesive may be injected by a syringe, not shown, having an elongated hollow needle introduced into the end portion 32′ of the sheath 16′ which has been flared to provide an enlarged mouth 62′, Figure 3. The rear end portion 32′ of the sheath 16′ projects outwardly from the cable anchoring portion 58′ of the shell 10′, when the biasing spring 17′ is compressed as shown in Figure 3, and the sheath 16′ is slid rearward of the shell 10′. The rear end portion 32′ sheaths the needle during entry and withdrawal from the sheath 16′. The shell 10′ is protected against touching by the needle and against deposition of adhesive. The needle is passed substantially along the interior of the sheath 16′ before depositing the quantity of adhesive within the body 15′ of the holder 13′. The adhesive is deposited near the front end 19′ of the body 15′, adjacent to the alignment ferrule 14′ and remote from the open rear end portion 32′ of the sheath 16′. The sheath 16′ prevents leaking of the adhesive from the holder 13′ and prevents the adhesive from spreading over the spring 17′ and the shell 10. Upon expansion of the coils of the biasing spring 17′, the sheath 16′ is retracted within the shell 10′. The cable 2 is passed successively along the interiors of the strain relief boot 9′, the sleeve 68 and the crimp ferrule 8′. The buffer covered fiber 3,4 of the cable 2 is assembled in the rear end 58′ of the shell 10′ and into and along the sheath 16′. The sheath 16 internal diameter receives and guides the buffer covered fiber 3,4 for assembly along the passageway 24′ of the body 15′. The entry 25′ of the passageway 24′ guides a fiber 3 of the cable 2 into the bore 28′ of the alignment ferrule 14′. The periphery of the entry encircles and supports the buffer covered fiber 3,4. The front end of the fiber 3 is exposed at a front end 63′ of the alignment ferrule 14′ and is finished with an optical face, by a known procedure of polishing or fracturing. The sheath 16′ closely encircles a buffer 4 of the buffer covered fiber 3,4 to prevent wicking of the adhesive along the buffer covered fiber 3,4 to such an extent that the adhesive leaks from the open rear end of the sheath 16′. The adhesive will be brought into contact with and will coat the fiber 3 and the buffer covered fiber 3,4 and further, will be urged forwardly of the holder 13′ by the buffer covered fiber 3,4 as the buffer covered fiber 3,4 moves forwardly of the sheath 16′ and of the body 15′ and of the alignment ferrule 14′. It is not necessary for the adhesive to wick in a direction rearward of the buffer covered fiber 3,4 or rearwardly of the holder 13, since the adhesive is desired only to bond the buffer covered fiber 3,4 within the holder 13′, and the fiber 3 in the alignment ferrule 14′. The internal diameter of the shell rear end 58′ is smaller than the external diameter of a cable jacket 6. Thus the jacket 6 remains outside of the shell 10′, while the shell rear end 58′ opposes a front end 64′ of the cable jacket 6′. The strength members 5 are placed to overlap the exterior of the shell rear end 58. The crimp ferrule 8′ is displaced along the cable 2 to a position concentrically encircling the shell rear end 58′. Thereby, the strength members 5 are anchored to the shell rear end 58′. The crimp ferrule 8′ encircles the jacket 6 of the cable 2 where the jacket 6 projects adjacent to the shell 10′. The sleeve 68 is advanced along the cable 2 and is threadably secured to the coupling ring 18′. As shown in Figure 2, the sleeve 68 encircles the rear end portion 12′ of the shell and the crimp ferrule 8′. The end 71 of the sleeve 68 encircles the cable 2, Figure 8, and transfers bending stress from the cable to the coupling ring 18′. The strain relief boot 9′ is advanced along the cable 2 to encircle the crimp ferrule 8′ and the jacket 6 of the cable 2 where the jacket 6 projects adjacent to the end 71. The connector 1′ is shown connected to a complementary alignment connector 72 having an alignment passage 72 and an alignment sleeve 74 in the passage 73 and receiving a ferrule 14′ therein. The coupling ring 18′ is coupled to bayonet springs, not shown, on the exterior of the alignment connector 72. The finger 34′ is slidably received along an open end slot 76 of the alignment connector 72 to prevent relative rotation of the ferrule 14′. An advantage of the invention is that the coupling ring 18′ is permitted relative rotation in a space separating the flange 7′ and the spring clip 56′, while the coupling ring 18′ and the sleeve 68, together with the strain relief boot 9′, are reciprocatable and rotatable relative to the component parts of the connector 1′ and the complementary alignment connector 72, during connection and disconnection of the coupling ring 18′ with the complementary connector 72, and while the ferrule 14′ and the shell 10′ are prevented from relative rotation. If desired, relative rotation between the strain relief body 9′ and the sleeve 68 can occur when the sleeve 68 is rotated with rotation of the coupling ring 18′. This allows relative rotation as well as relative reciprocation of the coupling ring 18′ to permit full seating of the coupling ring 18′ with the bayonet prongs to connect to, or disconnect from to the complementary alignment connector 72, while the sleeve 68 and strain relief boot 9′ remain fully assembled with the coupling ring 18′. The buffer covered fiber 3,4 and the holder 13, are joined together as a unit by the adhesive for reciprocation and axial slidable displacement with respect to the shell 10′ and the coupling ring 18′ and the strength members 5 and the jacket 6 of the cable 2. The end of the alignment ferrule 14′ engages a portion of a complementary connector, not shown, in the alignment sleeve 74, and is slidably biased rearwardly of the connector 1 against the bias of the spring 17′. The bias of the spring 17′ will urge the end 63′ of the ferrule 14′ in a direction forwardly of the connector 1′ and engaged against the portion of the complementary connector, to maintain a desired alignment of the optical face of the fiber 3 with the portion of the complementary connector. According to an aspect of the invention, the strength members 5 of the cable 2 are anchored to the shell 10′, whereby the strength members 5 and the shell 10′ are connected together as a unit. Should a tensile force be applied to the cable 2, the force will be transmitted along the shell 10′ and to the coupling ring 18′ and to the complementary alignment connector 72. The spring bias on the holder 13′ is not disturbed by the tensile force. The buffer covered optical fiber 3,4 is not slidably displaced by the tensile force, and the desired alignment of the optical face of the fiber 3 is not disturbed, and the desired engagement of the ferrule 14′ with complementary connector is not disturbed.

Claims: A connector (1′) for an optical fiber cable (2), wherein the cable includes: at least one optical fiber (3) having an outer layer of strength members (5), and wherein the connector includes: at least one elongate tubular holder (13′) which is for holding a corresponding optical fiber (3); a tubular shell (10′) which telescopically fits onto a rear end portion of the holder (13′) and is connectable to the strength members (5); and an outer coupling ring (18′) which fits over the shell (10′) and which has means for connection or disconnection with respect to a complementary connector (72), the connector (1′) being characterised in that the shell (10′), the coupling ring (18′) and the holder (13′) are constructed so that the coupling ring (18′) is rotatable but is not reciprocatable with respect to the shell (10′) and is reciprocatable and rotatable with respect to the holder (13′;), and further characterised in that a sleeve (68) secured to the rear of the coupling ring (18′) is reciprocatable and rotatable with the coupling ring (18′) during connection and disconnection to a complementary connector (72), and serves to transfer the bending forces from the cable (2) to the coupling ring (18′). A connector as claimed in claim 1, further characterised by means for anchoring the strength members (5) to the shell (10′). A connector as claimed in claim 1 or 2, further characterised in that the rear portion of the holder (13′) comprises a sheath (16′) and the corresponding optical fiber (3) extends along inside the sheath (16′). A connector as claimed in claim 1, 2 or 3, further characterised by a strain relief (9′) which fits over a rear portion of the shell (10′) to encircle at least a portion of the cable (2) projecting from the shell (10′).

Inventors: ABENDSCHEIN FREDERIC HENRY, GERACE JEFFREY THOMAS, PLOTTS ALAN EDWARD, ABENDSCHEIN, FREDERIC HENRY, GERACE, JEFFREY THOMAS, PLOTTS, ALAN EDWARD
Applicants: WHITAKER CORP, THE WHITAKER CORPORATION
Application year: 1990
Main classification: G02B6
IPC codes: G02B6