Patent Publication Number: US-10782489-B2

Title: Fiber optic connector

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a Divisional of U.S. application Ser. No. 15/482,981, now matured to U.S. Pat. No 10,473,859, itself claims benefit of U.S. provisional application Ser. No. 62/320,425 filed Apr. 8, 2016. All documents above are incorporated herein in their entirely by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a fiber optic connector. 
     BACKGROUND TO THE INVENTION 
     The prior art discloses fiber optic connectors terminated by a ferrule and comprising a fiber optic stub spliced to a stripped end of an optic fiber. One drawback of these fiber optic devices is that the splice point between the stub and the stripped end are relatively weak and can become damaged by in advertent bending or by pulling on the fiber optic cable. 
     SUMMARY OF THE INVENTION 
     In order to address the above and other drawbacks there is provided A fiber optic connector assembly. The assembly comprises a fiber optic stub terminated at a first end by a ferrule and a second end spliced at a splice point to a length of fibre optic cable, a mechanical support comprising at least one of a square bar and an elongate plate positioned in parallel and adjacent to the stub and the fiber optic cable straddling the splice point, the elongate plate comprising a concave inner surface conforming substantially to an outer surface of the stub and the fiber optic cable, and an elongate flexible tube completely and snugly encasing the mechanical support and the stub and the fiber optic cable adjacent the mechanical support. 
     There is also provided a method of assembling a fiber optic connector comprising splicing a second end of a fiber optic stub to a stripped end of a fiber optic cable at a splice point, a first end of the stub terminated by a ferrule, positioning a mechanical support comprising one of an elongate square bar and an elongate plate comprising a concave surface adjacent the stub and the fiber optic cable straddling the splice point, and snugly surrounding the mechanical support with a flexible tube. 
     Additionally, there is provided a fiber optic connector for terminating a fiber optical cable assembly comprising a fiber optic cable, a plurality of elongate strengthening strands positioned along the fiber optic cable and a cable jacket covering the fiber optic cable and the strengthening strands, the connector comprising: a fiber optic stub terminated at a first end by a ferrule and spliceable at a second end to a stripped end of the fibre optic cable, a housing for receiving the fiber optic stub at a first end and the fiber optic cable at a second end, the housing second end comprising a threaded outer surface and a plurality of strand receiving grooves intersecting the threaded outer surface and arranged substantially in parallel to a housing axis, and an elongate flexible boot comprising a first end comprising a threaded inner surface configured for engagement with the threaded outer surface, wherein the strengthening strands are retained within the plurality of strand receiving grooves by the threaded inner surface. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a pair of fiber optic connectors in accordance with an illustrative embodiment of the present invention; 
         FIGS. 2A and 2B  are perspective views of a fusion splice in accordance with an illustrative embodiment of the present invention; 
         FIG. 3A  is an exploded perspective view of a middle portion of a fiber optic connector and duplex clip in accordance with an illustrative embodiment of the present invention; 
         FIG. 3B  is a perspective view of an assembled middle portion of a fiber optic connector and duplex clip in accordance with an illustrative embodiment of the present invention; 
         FIG. 4A  is an exploded perspective view of a middle portion of a fiber optic connector and duplex clip in accordance with an alternative illustrative embodiment of the present invention; and 
         FIG. 4B  is a perspective view of an assembled middle portion of a fiber optic connector and duplex clip in accordance with an alternative illustrative embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS 
     Referring now to  FIG. 1 , a fiber optic connector in accordance with an illustrative embodiment of the present invention, and generally referred to using the reference numeral  10 , will now be described. The fiber optic connector  10  is generally configured to, as will be described in more detail hereinbelow, terminate an optic fiber cable  12  comprising an optic fiber (not shown) surrounded by a cable jacket  14 . Strands of strengthening yarn (also not shown) such as fabricated from aramid or Kevlar or the like are provided between the optic fiber and jacket  14 . The connector  10  comprises a plug portion  16 , illustratively an LC compatible plug portion, comprising a ferrule  18  (shown covered) and suitable for insertion into an LC compatible receptacle  20 . The connector  10  further comprises a middle portion  22 , as will described in more detail below, a fusion splice (not shown) and a boot portion  24  which engages with the jacket  14  and aramid strands of the fiber optic cable  12  to provide a robust interconnection. Although an LC compatible plug and receptacle have been used in this illustrative embodiment, a person of ordinary skill in the art will now understand that other single fiber technologies, such as SC and ST could also be used. Additionally, and in a particular embodiment, a fiber optic cable comprised of a plurality of optic fibers and a multifibre compatible plug and receptacle such as MPO could be used. 
     Referring now to  FIGS. 2A and 2B  in addition to  FIG. 1 , the middle portion  22  comprises a first end  26  which engages the plug portion  16 , for example through the provision of tabs  28  which engage complementary slots  30  in the plug portion  16 , and a second end  32  comprising a threaded outer surface  34  which mates with a complementary threaded ring  36  on the boot portion  24 . The boot portion  24  further comprises a tapered flexible boot  38  which, when assembled, covers an end portion of the optic fiber cable  12 . The threaded ring  36  is rotatable versus the tapered boot  38  and such that it can be easily threaded onto the threaded outer surface  34 . The threaded ring  36  further comprises a plurality of teeth  40  which, when threaded onto the threaded outer surface  34 , engage complementary teeth  42  on the middle portion  22 , thereby preventing the threaded ring  36  from inadvertently being unthreaded. Additionally, a series of grooves  44  arranged lengthwise intersect the threads  46  of the threaded outer surface  34  and such that the strands of aramid yarn (not shown) are received therein. The grooves  44  accept strands of the yarn preventing them from being twisted while the threaded ring  36  is being mated with the threaded outer surface  34  which otherwise might rotate the optic fiber causing it to break or become distorted. 
     Referring to  FIG. 3A  in addition to  FIGS. 2A and 2B , in a first embodiment the middle portion  22  houses a fusion splice  48  comprising a shrinkable outer tube  50  housing an inner tube  52  fabricated from an adhesive. Illustratively the outer tube  50  is heat shrinkable and the inner the  52  manufactured from a material which melts when heated, and a mechanical support  54 . The support  54  illustratively comprises an elongate plate  56  manufactured from a rigid yet slightly bendable material such as metal or the like and having a concave cross section and which conforms generally to the inner surface  58  of the shrinkable tube  50 . Illustratively, in one embodiment the elongate plate  56  comprises generally in cross section C shaped embossments  60  at either end for improving mechanical strength while the thinner mid-section  54  insures a tight fit about the centre point P. 
     Still referring to  FIG. 3A , in use, in order to assemble the fusion splice  48  an optic fiber  64  comprising a splice point  66  is inserted into the inner tube  52  and the splice point  66  arranged so it is positioned adjacent the centre point P. In this regard, the splice point is between a stub portion  68  which is terminated at a distal end by the ferrule (reference  18  in  FIG. 1 ) and a second length of fiber optic cable  70 . The support  54  is placed adjacent and in parallel to the inner tube  52  and this subassembly inserted into the shrinkable outer tube  50  ( FIG. 3B ). In a particular embodiment, the assembly is then lightly heated such that the shrinkable outer tube  50 , manufactured from a heat shrinkable material, shrinks and the inner tube  52  melts. The mechanical support  54  provides for increased mechanical strength and in combination with the other components of the fusion splice  48  results in a robust assembly. 
     Referring back to  FIG. 3A , in particular embodiment the fusion splice  48  comes preassembled with the inner tube  52  and mechanical support  54  within the shrinkable outer tube  50 . On assembly, the second length optic fiber  70  is inserted into the inner tube  52 , spliced to the stub portion  68  and then retracted into the inner tube  52  until the splice point  66  is positioned adjacent the centre point P. The shrinkable outer tube  50  is then shrunk, for example through the application of heat, to complete the assembly. 
     Referring back to  FIGS. 2A and 2B , the resultant the fusion splice  48  is positioned within the housing  22  along the axis A-A with the Kevlar/aramid yarn strengthening strands positioned within the grooves  44 . The boot  24  is then threaded onto the rearward end of the housing until the teeth  40  are engaged by the complementary teeth  42  on the housing  22 . 
     Referring now to  FIG. 4A , in an alternative embodiment of the fusion splice  48 , the mechanical support  54  comprises a bar  72 , such as a square metal wire or glass bar. Illustratively, the bar  72  is of a square shaped cross section. 
     Still referring to  FIG. 4A , during assembly of the fusion splice  48  the optic fiber  64  comprising the splice point  66  is inserted into the inner tube  52  and the splice point  66  arranged so it is positioned adjacent the centre point P. In this regard, the splice point is between the stub portion  68  which is terminated at a distal end by the ferrule (reference  18  in  FIG. 1 ) and the second length of fiber optic cable  70 . The bar  72  is placed adjacent and in parallel to the inner tube  52  and this subassembly inserted into the heat shrinkable outer tube  50  ( FIG. 4B ). The assembly is then lightly heated such that the heat shrinkable outer tube  50  shrinks and the inner tube  52  melts. The bar  72  provides for increased mechanical strength and in combination with the other components of the fusion splice  48  results in a robust assembly. 
     Although the present invention has been described herein above by way of specific embodiments thereof, it can be modified without departing from the spirit and nature of the subject invention as defined in the appended claims.