Patent Publication Number: US-2022229243-A1

Title: Mechanical interface between a fiber optic cable and a fiber optic connector

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of application Ser. No. 16/999,156, filed Aug. 21, 2020, which is a continuation of application Ser. No. 16/363,636, filed Mar. 25, 2019, now U.S. Pat. No. 10,754,102, which is a continuation of application Ser. No. 15/707,252, filed Sep. 18, 2017, now U.S. Pat. No. 10,247,888, which is a continuation of application Ser. No. 14/176,940, filed Feb. 10, 2014, now U.S. Pat. No. 9,766,413, which application is a divisional of application Ser. No. 12/782,929, filed May 19, 2010, now U.S. Pat. No. 8,646,989, issued Feb. 11, 2014, which application claims the benefit of provisional application Ser. No. 61/179,673, filed May 19, 2009, which applications are incorporated herein by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to fiber optic data transmission, and more particularly to fiber optic cable connection systems. 
     BACKGROUND 
     Fiber optic cables are widely used to transmit light signals for high speed data transmission. The fiber optic cables include an optical fiber or optical fibers. The optical fibers function to carry the light signals (i.e., optical signals). A typical optical fiber includes an inner core surrounded by a cladding that is covered by a coating. 
     Fiber optic cable connection systems are used to facilitate connecting and disconnecting the fiber optic cables in the field without requiring a splice. A typical fiber optic cable connection system for interconnecting two fiber optic cables includes fiber optic connectors (i.e., optical fiber connectors) mounted at ends of the fiber optic cables, and an adapter for mechanically and optically coupling the fiber optic connectors together. The fiber optic connectors generally include ferrules that support ends of the optical fibers of the fiber optic cables. End faces of the ferrules are typically polished and are often angled. The adapter includes co-axially aligned ports (i.e., receptacles) for receiving the fiber optic connectors desired to be interconnected. The adapter generally includes an internal sleeve that receives and aligns the ferrules of the fiber optic connectors when the connectors are inserted within the ports of the adapter. 
     With the ferrules and their associated fibers aligned and abutted within the sleeve of the adapter, a fiber optic signal can pass from one fiber to the next corresponding fiber via an optical interface created by this arrangement. The adapter also typically has a mechanical fastening arrangement (e.g., a snap-fit arrangement, a latch, etc.) for mechanically retaining the fiber optic connectors within the adapter. 
     Fiber optic cables are currently being routed to customer premises (e.g., fiber-to-the premises). During installation of fiber optic cable in buildings, pulling eyes attached to fiber optic connectors are used to pull fiber optic cables through conduits within the building. The use of pulling eyes attached to fiber optic connectors to pull fiber optic cables through conduits places tension on the mechanical interfaces between the fiber optic connectors and their corresponding fiber optic cables. This can cause the mechanical interfaces to fail under the tension loading. Additionally, during installation of connectorized fiber optic cables, side loads/bending moments can be applied to the fiber optic connectors thereby causing breakage. 
     SUMMARY 
     One aspect of the present disclosure relates to a mechanical interface between a fiber optic connector and a fiber optic cable that can withstand relatively high tension loading without failing. In one embodiment, the mechanical interface can withstand at least 75 pounds of tensile loading. 
     Another aspect of the present disclosure relates to a fiber optic connector having a front end with a ferrule and a rear end adapted to be mechanically coupled to a fiber optic cable. The rear end of the fiber optic connector is configured to resist breakage caused by side loadings/bending moments applied to the fiber optic connector. 
     A variety of additional inventive aspects will be set forth in the description that follows. The inventive aspects can relate to individual features and to combinations of features. It is to be understood that both the forgoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the broad inventive concepts upon which the embodiments disclosed herein are based. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a fiber optic cable and connector assembly in accordance with the principles of the present disclosure, the perspective view showing a proximal end of the fiber optic cable and connector assembly; 
         FIG. 2  is another perspective view of the fiber optic cable and connector assembly of  FIG. 1 , the perspective view showing a distal end of the fiber optic cable and connector assembly; 
         FIG. 3  is a cross-sectional view of the fiber optic cable and connector assembly of  FIG. 1 , the cross-sectional view taken at a plane illustrated at  FIG. 2 ; 
         FIG. 4  is an enlarged portion of  FIG. 3 ; 
         FIG. 5  is a cross-sectional view of another fiber optic cable and connector assembly in accordance with the principles of the present disclosure, the cross-sectional view taken through a pair of pins of the fiber optic cable and connector assembly; 
         FIG. 6  is an enlarged portion of  FIG. 5 ; 
         FIG. 7  is a cross-sectional view of another fiber optic cable and connector assembly in accordance with the principles of the present disclosure, the cross-sectional view taken through a pair of pins of the fiber optic cable and connector assembly; 
         FIG. 8  is an enlarged portion of  FIG. 7 ; 
         FIG. 9  is a cross-sectional view of another fiber optic cable and connector assembly in accordance with the principles of the present disclosure, the cross-sectional view taken through a pair of pins of the fiber optic cable and connector assembly; 
         FIG. 10  is an enlarged portion of  FIG. 9 ; 
         FIG. 11  is a cross-sectional view of another fiber optic cable and connector assembly in accordance with the principles of the present disclosure, the cross-sectional view taken through a pair of pins of the fiber optic cable and connector assembly; 
         FIG. 12  is an enlarged portion of  FIG. 11 ; 
         FIG. 13  is a cross-sectional view of another fiber optic cable and connector assembly in accordance with the principles of the present disclosure, the cross-sectional view taken through a pair of pins of the fiber optic cable and connector assembly; 
         FIG. 14  is an enlarged portion of  FIG. 13 ; 
         FIG. 15  is a cross-sectional view of another fiber optic cable and connector assembly in accordance with the principles of the present disclosure, the cross-sectional view taken through a pair of pins of the fiber optic cable and connector assembly; 
         FIG. 16  is an enlarged portion of  FIG. 15 ; 
         FIG. 17  is a cross-sectional view of another fiber optic cable and connector assembly in accordance with the principles of the present disclosure, the cross-sectional view taken through a pair of pins of the fiber optic cable and connector assembly; and 
         FIG. 18  is an enlarged portion of  FIG. 17 . 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1 and 2  show a fiber optic cable and connector assembly  20  in accordance with the principles of the present disclosure. The fiber optic connector and cable assembly  20  includes fiber optic cable  22  mechanically connected to a fiber optic connector  24  at a mechanical interface  26 . The fiber optic cable  22  includes a plurality of optical fibers  28  (e.g., 12 fibers, 24 fibers, or any other number of fibers) having end portions that terminate at a ferrule  30  of the fiber optic connector  24 . The end portions of the optical fibers  28  are typically secured (e.g. with epoxy) within openings defined by the ferrule  30  and have polished ends  32  (shown schematically at  FIG. 2 ) located at an end face  34  of the ferrule  30 . The ferrule  30  can include alignment structures (e.g., pins  36 , pin receivers, or other structures) for aligning the ferrules of two connectors desired to be connected together. When two fiber optic connectors are connected together, the polished ends  32  of their respective optical fibers  28  are preferably placed in co-axial alignment with one another such that optical transmissions can readily be transferred from fiber to fiber. 
     Referring to  FIGS. 3 and 4 , the fiber optic connector  24  includes a main connector body  36  having a distal end  38  positioned opposite from a proximal end  40 . A release sleeve  42  is slidably mounted about the main connector body  36  at a location between the distal end  38  and the proximal end  40 . The release sleeve  42  can be slidably retracted on the main connector body  36  to disengage the fiber optic connector  24  from a fiber optic adapter. The ferrule  30  mounts at the distal end  38  of the main connector body  36  and a spring push  44  mounts at the proximal end  40  of the main connector body  36 . The spring push  44  engages a spring  46  (shown only at  FIG. 3  for clarity) positioned within the main connector body  36  that biases the ferrule  30  in a distal direction. The spring push  44  is secured to the main connector body  36  by a mechanical connection such as a snap-fit connection. 
     Referring back to  FIG. 1 , the optical fibers  28  of the fiber optic cable  22  are contained within an outer jacket  50 . The fiber optic cable  22  also includes strength members  52  positioned inside the outer jacket  50  and around the optical fibers  28 . In one embodiment, the strength members  52  are configured to provide the fiber optic cable  22  with tensile strength without substantially decreasing the flexibility of the fiber optic cable  22 . By way of example, the strength members  52  can include the plurality of flexible members such as aramid yarns (i.e., Kevlar). 
     The mechanical interface  26  includes a crimp supporting stub  54  (i.e., a barrel) that projects proximally outwardly from a main body of the spring push  44 , a crimp band  56 , and an outer boot  58 . The crimp band  56  can be made of a deformable metal material. In one embodiment, the crimp band  56  includes a first portion  60  connected to a second portion  62  by a radial in-step  64 . The first portion  60  is crimped over the crimp supporting stub  54  and has a larger transverse cross-dimension than the second portion  62 . The first portion  60  of the crimp band  56  functions to secure the strength members  52  of the fiber optic cable  22  to the fiber optic connector  24 . Specifically, the strength members  52  are mechanically crimped between the first portion  60  and the outer surface of the crimp supporting stub  54 . The second portion  62  is crimped down on the outer jacket  50  of the fiber optic cable  22  to secure the outer jacket  50  to the fiber optic connector  24 . The outer boot  58  includes a distal end  66  that mounts over the crimp band  56  and a proximal end that mounts over the fiber optic cable  22 . The boot  58  can have a tapered configuration that transitions from a larger cross-dimension adjacent the distal end  66  to a smaller cross-dimension adjacent the proximal end  68 . 
     After crimping, the crimp band  56  can have a number of different transverse cross-sectional shapes. In one embodiment, the crimp band  56  can have a polygonal shape (e.g., a hexagonal shape) after crimping. When the crimp band  56  is crimped over the crimp supporting stub  54 , the crimp supporting stub  54  can deform to conform to/match the final shape of the crimp band  56 . For example, the crimp supporting stub  54  can have a polygonal shape after crimping. In other embodiments, the crimp band  56  can include at least portions that are generally cylindrical after crimping. 
     It is desirable for the mechanical interface  26  to be able to withstand an axial tension load of at least  75  pounds without failure (i.e., without the fiber optic connector  24  pulling away from the fiber optic cable  22 ). To improve the ability of the mechanical interface  26  to withstand high tensile loads, the first portion  60  of the crimp band  56  includes an inner surface  80  including strength member biting or gripping features  82  adapted for securely engaging the strength members  52  when the strength members  52  are crimped between the first portion  60  of the crimp band  56  and the crimp supporting stub  54 . In certain embodiments, the gripping features  82  can include helical threads, teeth, knurling, projections, bumps or other structures. In certain embodiments, the gripping features  82  have an undulating configuration with relatively sharp peaks and valleys such as those formed by a thread pattern tapped or otherwise formed within the interior of the crimp band  56 . In further embodiments, gripping features as described above can also be provided on the exterior surface of the crimp supporting stub  54 . In such embodiments, the gripping features of the crimp band and the gripping features of the crimp supporting stub cooperate to secure the strength members between the crimp band and the crimp supporting stub. 
     To further enhance the ability of the mechanical interface  26  to withstand relatively large tensile loads, the second portion  62  of the crimp band  56  can be provided with gripping features  84  for gripping the outer jacket  50  of a fiber optic cable  22 . As shown at  FIG. 3 , the gripping features  84  include through-holes defined radially through the second portion  62  of the crimp band  56 . When the second portion  62  of the crimp band  56  is crimped down on the outer jacket  50 , portions of the outer jacket  50  flow or otherwise deform into the through-holes  84  thereby providing a mechanical interlock that assists in maintaining engagement between the outer jacket  50  and the second portion  62  of the crimp band  56 . In other embodiments, the gripping features on the second portion  62  may include ridges, bumps, dimples, depressions, teeth, or other structures. 
       FIGS. 5 and 6  show an alternative fiber optic connector  124 . The fiber optic connector  124  has the same components as the fiber optic connector  24  except for the configuration of the spring push. Specifically, the spring push  44  of the fiber optic connector  24  has a solid, homogeneous molded plastic construction. In contrast, the spring push  144  has a composite structure including a metal insert piece  150  embedded within an over-molded plastic piece  152 . The metal insert piece  150  forms the crimp supporting stub of the spring push  144 . Additionally, the insert piece  150  extends across a region  156  of the spring push  144  thereby providing the region  156  with structural reinforcement. In this way, region  156  is better able to withstand bending loads without breaking. 
       FIGS. 7 and 8  show another fiber optic connector  224  in accordance with the principles of the present disclosure. The fiber optic connector  224  has the same components as the fiber optic connector  24  except the spring push and the crimp band have been modified. Specifically, the fiber optic connector  224  includes a spring push  244  defining an internal annular recess  245  that surrounds a central axis of the fiber optic connector  224 . The recess has an open end  247  that faces proximally outwardly from the spring push  244 . The recess  245  is configured to receive an extended portion  255  of a crimp band  256  such that the crimp band  256  extends into and reinforces the spring push  244  and the connector body against bending forces applied to the crimp supporting stub. The crimp band  256  also includes a first portion  260  crimped about the crimp supporting stub and a second portion  262  crimped on the outer jacket  50  of the fiber optic cable  22 . 
       FIGS. 9 and 10  show another fiber optic connector  324  in accordance with the principles of the present disclosure. The fiber optic connector  324  has the same components as the fiber optic connector  24  except the spring push and the crimp band have been modified. Specifically, the fiber optic connector  324  includes a crimp band  356  and a spring push  344 . The crimp band  356  includes an enlarged portion  357  that extends distally past the crimp supporting stub and fits over an enlarged region  345  of the spring push  344 . The crimp band  356  also includes a first portion  360  crimped about the crimp supporting stub and a second portion  362  crimped on the outer jacket  50  of the fiber optic cable  22 . Enlarged portion  357  of the crimp band  356  fits snugly over an enlarged portion  345  of the spring push  344  and reinforces the spring push against bending loads applied to the crimp supporting stub. The enlarged portion  345  of the spring push  344  has a smaller cross-dimension than the cross-dimension of the main body of the connector  324  such that a shoulder  390  is defined at the distal end of the spring push and the proximal end of the main body. The shoulder  390  allows the enlarged portion  357  of the crimp band  356  to be flush or almost flush with the outer surface of the main body of the fiber optic connector  324 . 
       FIGS. 11 and 12  show another fiber optic connector  424  in accordance with the principles of the present disclosure. The fiber optic connector  424  has the same components as the fiber optic connector  24  except the spring push and the boot have been modified. Specifically, the fiber optic connector  424  includes a boot  458  and a spring push  444 . The boot  458  includes an enlarged portion  457  that extends distally past the crimp supporting stub and fits over an enlarged region  445  of the spring push  444 . The boot  458  can include an internal reinforcing member  459  (e.g., a sleeve such as a metal sleeve). The enlarged portion  457  of the boot  458  fits snugly over an enlarged portion  445  of the spring push  444  and reinforces the spring push against bending loads applied to the crimp supporting stub. The enlarged portion  445  of the spring push  444  has a smaller cross-dimension than the cross-dimension of the main body of the connector  424  such that a shoulder  490  is defined at the distal end of the spring push and the proximal end of the main body. The shoulder  490  allows the enlarged portion  457  of the boot  458  to be flush or almost flush with the outer surface of the main body of the fiber optic connector  424 . 
       FIGS. 13 and 14  show another fiber optic connector  524  in accordance with the principles of the present disclosure. The fiber optic connector  524  has the same components as the fiber optic connector  24  except the spring push, the crimp band and the connector main body have been modified. The fiber optic connector  524  has a configuration in which a crimp band  556  is crimped over a spring push  544  and includes a crimped portion that extends inside a main connector body  536  of the fiber optic connector  524 . During assembly, the strength members  52  of the fiber optic cable are initially crimped onto the spring push  544 , and the spring push  544  is then snapped into the back end of the main connector body  536 . In this way, the crimp band  556  can be positioned to reinforce the spring push  544  with respect to bending, and in certain embodiments the distance that the crimp supporting stub projects outwardly from the main connector body  536  can be shortened. 
       FIGS. 15 and 16  show another fiber optic connector  624  in accordance with the principles of the present disclosure. The fiber optic connector  624  has the same components as the fiber optic connector  24  except a different crimping arrangement is being used. The crimping arrangement is adapted to be shorter in a direction along the longitudinal axis of the connector  624  thereby possibly reducing a bending moment applied to the crimp supporting stub when side loading is applied to the crimp supporting stub through the fiber optic cable and the boot. The crimping arrangement includes a first crimp band  656   a  for crimping the strength members  52  of the fiber optic cable  22  to the crimp supporting stub to secure the strength members  52  to the connector  624 . The crimping arrangement also includes a second crimp band  656   b  for crimping the cable jacket  50  over the first crimp band  656   b  to secure the outer jacket  50  to the connector  624 . The connector  624  also has a shortened boot  658 . 
       FIGS. 17 and 18  show another fiber optic connector  724  in accordance with the principles of the present disclosure. The fiber optic connector  724  has the same components as the fiber optic connector  24  except a different crimping arrangement is being used. The crimping arrangement is adapted to be shorter in a direction along the longitudinal axis of the connector  724  thereby possibly reducing a bending moment applied to the crimp supporting stub when side loading is applied to the crimp supporting stub through the fiber optic cable and the boot. The crimping arrangement includes a crimp band  756  for crimping the strength members  52  of the fiber optic cable  22  to the crimp supporting stub to secure the strength members  52  to the connector  724 . The fiber optic connector  724  also includes a shortened boot  758  having an internal reinforcing member  759  such as a metal reinforcing sleeve. The boot  758  compresses the outer jacket  50  of the fiber optic cable  22  against the outer surface of the crimp band  756  to secure the outer jacket  50  to the fiber optic connector  724 .