Abstract:
An apparatus for retaining and protecting spliced optical fibers. Optical fibers forming an extensive network, extending a great distance, are spliced together to provide the communication medium for the network. The apparatus includes a joint box for protecting the splices. Within the joint box is at least one arcuate-shaped splice retainer. The retainer secures the splices in a static position to prevent them from being damaged. Also, the retainer may include more than one arcuate layers for storing the splices. The arcuate layers organize the splices, so they are readily identifiable and accessible. In addition, the arcuate layers make efficient use of the limited space available for storing the splices. The joint box includes a center shelf longitudinally dividing the joint box into two compartments. To accommodate more splices, an arcuate retainer may be provided in each compartment by mounting an arcuate retainer on each side of the shelf.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is related to commonly assigned U.S. patent application Ser. No. 09/399,752, filed Sep. 21, 1999 and entitled “Fiber Retaining System;” and U.S. patent application Ser. No. 09/399,751, filed Sep. 21, 1999 and entitled “Fiber Retaining System,” both of which are hereby incorporated by reference herein. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to the retention and protection of spliced optical fibers. More specifically, the invention relates to an arcuate retainer for organizing and securing fiber optic splices. 
     BACKGROUND OF THE INVENTION 
     Communications networks are frequently made of many miles of optical fibers. Indeed, many of the networks can extend between continents and across oceans and other large bodies of water. For protection, the optical fibers are contained in a larger cable. An example of such a cable is shown in FIG.  1 . The cable  2  includes an outer insulating plastic coating  4 , a copper sheath  6  inside the outer coating  4 , and high strength members, such as steel wires  8 , inside of the copper sheath  6 . A loose tube  10  is contained within the steel wires  8 , and one or more isolated optical fibers  12  are contained within the loose tube  10 . This permits the fibers  12  to move with respect to the steel wires  8 , the sheath  6  and the coating  4 . This cable arrangement has been found to be desirable in many high strength applications. 
     As neither the cables nor the fibers can be made and deployed in infinite lengths, sections of the cables and the fibers are attached together. The fibers are typically attached to each other by a process known as splicing. For protection from the environment, these spliced sections are commonly contained in a watertight housing, which is frequently referred to as a joint box. Such housings or joint boxes are also used when it is necessary to make splices in the field. 
     In circumstances when tension is applied to the cable, such as during the deployment of the cable underwater by a ship, it is undesirable to have the splice absorb the forces. Thus, on either side of the splice, a great deal of slack, such as three feet of fibers, may be provided to prevent the splice from being stressed. The joined fibers, with their slack, may be coiled onto a center section of the joint box, wound around cylinders or stored in magazines adjacent a center section of the joint box. The splice itself is fixed within the center section. 
     Traditionally, multiple splices are placed in each joint box. However, most arrangements do not make efficient use of the limited space in a joint box and do not adequately restrain splices to prevent damage. Thus, a need exists to organize splices in a manner that does not lend itself to damaging the splices and makes efficient use of limited space in a joint box. 
     SUMMARY OF THE INVENTION 
     In view of the foregoing, it is an aspect of the present invention to provide an arrangement for organizing and protecting spliced optical fibers in a joint box. 
     It is a further aspect of the present invention to provide an arcuate splice retainer for retaining a plurality splices. The retainer may be in a joint box and may include a first arcuate-shaped storage channel for retaining more than one of the plurality of splices. The retainer may include a first element having a convex surface forming a bottom portion of the first channel, and a second element having a concave surface forming a top portion of the first channel and retaining the more than one splices in the first channel between the first and second elements. The first element may include a center step and end steps in the lateral ends of the first element. The center step and the end steps may extend the length of the first retainer. The retainer may further include a second arcuate-shaped storage channel for storing more than one of the plurality of splices, wherein the second channel is radially spaced from the first channel with respect to a longitudinal axis parallel to longitudinal axes of said plurality of splices. The retainer may also include a third element having a concave surface forming a top portion to the second channel, and the second element having a convex surface forming a bottom portion to the second channel. The splices in the first and second channel may be secured in a static position. The retainer may further include a third arcuate-shaped storage channel angularly spaced from the first channel and radially spaced from the second channel with respect to the longitudinal axis, wherein the third channel is for retaining more than one of the plurality of splices, and the first and third channels are separated by the center step. The second element may be removably attached to said first element, and the third element may be removably attached to the second element. 
     A further aspect of the present invention may include a joint box with a middle section and a center shelf. The center shelf may longitudinally divide the middle section into first and second compartments, and a first retainer may be positioned on the center shelf in the first compartment. A second retainer may be positioned on the center shelf in the second compartment. 
     Another aspect of the present invention may include a fiber optical network, and the joint box and splices of the present invention may be a part of the fiber optical network. 
     The above and other features and advantages of the present invention will be readily apparent and fully understood from the following detailed description of preferred embodiments, taken in connection with the appended drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an isometric view of a cable; 
     FIG. 2 is a schematic top view of the joint box and the arcuate retainer of the present invention; 
     FIG. 3 is a schematic side sectional view of the joint box and the arcuate retainer of the present invention; 
     FIG. 4 is a perspective view of the joint box and the arcuate retainer of the present invention; 
     FIG. 5 is a cross-sectional view of the arcuate retainer; taken through line  5 — 5  of FIG. 2; and 
     FIG. 6 is a perspective view of the arcuate retainer shown partially assembled. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Details of the cable and fiber joining system for housing and protecting spliced optical fibers are shown in FIGS. 2-6. FIG. 2 schematically depicts the housing or joint box  20  connecting the free ends of two cables  2  together. The joint box  20  and optical fibers  12  are preferably part of an extensive fiber optical communications network that may extend long distances, e.g. below a large body of water. The cables  2  are preferably of the type shown in FIG. 1 such that the optical fibers  12  can move longitudinally with respect to the remainder of the cable  2 . The optical fibers  12  of the cables  2  are joined by splicing the fiber ends, using any well-known method, and creating splices  5 . The splices  5  are preferably reinforced with protective sleeves  9  (see FIG. 6) at the area of the splice for protecting the fiber connection. Sufficient slack  13  in the fibers  12  is provided to prevent the splices  5  from being stressed or pulled into one of the cables  2 . The slack  13  from the fibers  12  may be coiled onto the shelf  52 . 
     The joint box  20  includes cable termination sections  24  at its longitudinal ends, and a center section  22  disposed between, and connecting, the cable termination sections  24 . Each cable termination section  24  includes a body  26  with a cone-shaped hollow cavity therein, and a cone-shaped plug and sleeve configuration  28  that fits within the hollow cavity. The high strength steel wires  8  of the cables  2  are clamped between the hollow cavity of the body  26  and the plug and sleeve  28 , and the outer surface of the sleeve is malleable, which deforms around the high strength steel wire  8  as the plug is inserted. The body  26  and the plug and sleeve configuration  28  are hollow along their central axis  30 . This enables the fibers  12  to extend unrestrained therethrough. 
     The center section  22  is disposed between and connected to the cable termination sections  24 , and houses and protects the spliced section of the fibers  12 . The center section  22  is attached to the cable termination sections  24  by a bayonet-type locking arrangement or any known desirable arrangement. The joint box  20  also includes a cover  14  (see FIG. 5) for enclosing its interior. 
     In a preferred embodiment, the center section  22  includes a shelf  52  that generally divides the center section  22  into upper and lower compartments or sections  32  and  34 , as shown in FIG.  3 . In such an arrangement, an arcuate retainer  92  can be included on one or both of the upper and lower sides of the shelf  52 . FIG. 3 shows an arcuate retainer in upper compartment  32 , and an arcuate retainer in lower compartment  34 , shown with dashed lines, which may be provided to accommodate more splices. However, it is recognized that a shelf  52  need not be provided and that a single arcuate retainer  92  may be used. 
     FIGS. 2-6 show the arcuate retainer  92  for storing and securing the splices  5  in a static position. The retainer  92  includes a base  93  having a portion with an upper surface  96  having an arcuate shape. The base  93  is preferably removably attached to shelf  52  with screws  21 . However, the base  93  may be formed as part of the shelf  52  or permanently attached to the shelf  52 . The upper surface  96  preferably includes a center step  61  and lateral steps or ledges  62  in the base  93  on opposing sides of center step  61 . Each of the steps  61  and  62  extend longitudinally, preferably for the length of the arcuate retainer  92 . The steps  61  and  62  help define an area for organizing and placing splices  5  on the base when a middle cover  94  is attached to the base  93 . Also, the center step  61  divides the area for storing the splices  5 . As shown in FIG. 5, the splices  5  are placed on the arcuate outer convex surface  96  of base  93 . The center step  61  of the base  93  divides the area for storing splices  5  into two sections  100  and  101  which are arcuate-shaped storage channels. Sections  100  and  101  are curved in a plane perpendicular to the longitudinal axis of the splices  5  stored in the sections. In addition sections  100  and  101  are angularly spaced from a longitudinal axis  7 . By providing two storage sections  100  and  101 , the splices  5  are organized, so the fibers  12  connected to the splices  5  are less susceptible to being tangled. In addition, organizing the splices  5  in two sections allows the splices  5  to be quickly identified, since the splices  5  are not all grouped together. This can be beneficial when utilizing fibers in multiple bundles. Also, if desired, the upper surface  96  may be grooved (not shown) or otherwise subdivided, so each splice can fit in between two grooves when placed on the base. The grooves can help maintain the splices  5  in a static position when the splices  5  are secured by a cover. 
     As shown in FIG. 5, the middle cover  94  rests on the center step  61  and the lateral ends  64  of the base  93 . The middle cover  94  includes a concave lower surface  98  that provides the top boundary of storage sections  100  and  101 . Like base  93 , middle cover  94  includes a center step  71  and lateral steps or ledges  72  on opposing sides of the center step  72  in the lateral ends of the middle cover  94 . Each of the steps  71  and  72  extend longitudinally, preferably the length of the retainer  92 . The steps help define additional areas  102  and  103  for organizing and placing splices  5 . The lateral steps  72  also help support splices  5 . In addition, the center step  71  of middle cover  94  divides the area for storing the splices into two sections  102  and  103  which are arcuate-shaped channels. Similar to sections  100  and  101 , sections  102  and  103  are angularly spaced from the longitudinal axis  7  of the joint box  22 , and sections  102  and  103  are curved in a plane perpendicular to the longitudinal axis of the splices stored in the sections. Also, as shown in FIG. 5, sections  100  and  101  are radially spaced from sections  102  and  103  respectively, and sections  100  and  101  are radially and angularly spaced from sections  103  and  102  respectively. 
     The middle cover  94  is preferably removably attached to the base  93  with recessed middle cover screws  105 . The middle cover screws  105  are positioned on the lateral sides of the lateral steps  72  and on the top of center step  71  in order to affix middle cover  94  to the center step  61  and lateral steps  62  of the base  93 . The screws  105  extend through the middle cover  94  into the base  93 . When middle cover  94  is screwed into the base  93 , the splices  5  in sections  100  and  101  are secured by the middle cover  94  against the base  93 . The width of each of the storage sections  100 - 103  is generally the same as the width of a splice  5 , except the width of each of the storage sections  100 - 103  is slightly less in order to provide a light clamping force. The length of the screw hole for screws  105  are designed so that when the middle cover  94  is screwed into the base  93 , enough pressure is applied to the splices  5  in sections  100  and  101  to provide the light clamping force to secure the splices in a static position without damaging the splices  5 . Also, the middle cover  94  includes an arcuate convex upper surface  97  for placing splices  5  thereon. If desired, the upper surface  97  may be grooved or subdivided as described for upper surface  96 . 
     A top cover  95  includes a concave lower surface  107  that provides the top portion of the storage sections  102  and  103 . The top cover  95  is removably attached to the middle cover  94  with top cover screws  106  that affix the top cover  95  to the center step  71 . Other top cover screws  106  affix the top covers  95  to the lateral sides of the lateral steps  72  of middle cover  94 . It is recognized that the screws  105  and  106 , and their associated holes are positioned to avoid interference with one another. The top cover  95  secures the splices  5  in sections  102  and  103  against the middle cover  94  without damaging the splices  5 . 
     The arcuate shape of the base  93  and covers  94  and  95 , which define arcuate storage sections  100 - 103 , make efficient use of the limited space in a joint box for storing the maximum number of splices. Indeed, the joint box  20  is preferably circular in cross section, and the arcuate shapes of the splice storage sections  100 - 103  are preferably generally radial. Accordingly, this maximizes the storage space inside the joint box  20 . Additionally, the arcuate shape allows the splices to be layered and organized, so the splices are readily identifiable and accessible. 
     The base  93  as shown is generally circularly shaped, but the base  93  may be oval, square, octagonal or any desirable shape. 
     Although, the preferred embodiment of arcuate retainer  92  includes two layers of fibers, the arcuate retainer may include more than two covers to accommodate more than two layers of fibers. Furthermore, any desirable arrangement for removably attaching the covers may be implemented. Also, the covers  94  and  95  and the base  93  may be made of high strength steel or other materials with the requisite strength and durability. In addition, if desired, a metal cover, not shown, is attached around the body  3 , and a plastic sleeve, also not shown, may sealingly surround the entire joint box  20  in a conventional manner for waterproofing and insulating purposes. 
     The present invention has been described in terms of preferred and exemplary embodiments thereof. Numerous other embodiments, modifications and variations within the scope and spirit of the appended claims will occur to persons of ordinary skill in the art from a review of this disclosure.