Abstract:
A fiber bending apparatus for bending an optical fiber in a networking device and an optical fiber management system and method are provided. The fiber bender has an arcuate main body which is attached to the end of an optical fiber above the male connector and partially including the connector boot, bending the fiber substantially orthogonal to a direction from which the fiber is connected to a line module of the networking device, i.e., substantially parallel to the faceplate of the line module. In this way, the optical fibers are made to bend away from the chassis of the networking device, thereby preventing them from being crushed when the door of the chassis is closed. The optical fibers are also shielded from inadvertent impacts when a technician is working on the networking device. By enabling the optical fibers to be easily directed and managed, the overall fiber density of the networking device may be increased, thereby increasing its bandwidth and information processing capabilities.

Description:
This application is a Divisional of application Ser. No. 09/916,980 filed on Jul. 27, 2001, now U.S. Pat. No. 6,674,951, the entire contents of which are hereby incorporated by reference and for which priority is claimed under 35 U.S.C. § 120. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention relates to devices which employ optical fiber; more specifically, the invention relates to a device, system, and method of managing optical fibers in a way to keep them neat and protected from harm. 
   2. Description of Related Art 
   Modern computer and telecommunications networks are constantly growing more complex and have an ever-expanding need for bandwidth (the ability to accept, process, and/or transmit information). Many of the components used in such networks utilize optical transceivers and optical fibers as the means of communicating among and within the various components. 
   One of the ways that optical network components can be made more efficient is by providing them with a greater density of optical transceivers and fibers. One cannot merely increase the density on whim since optical fibers, however small they may be, do occupy space, and the housing or chassis in which they are disposed is finite in volume. Specific and carefully contemplated fiber connection schemes therefore must be employed. 
   Typically, optical transceivers are mounted in groups on a single card called a line module or line card. Often, optical fibers are connected directly to the transceivers, passing through the faceplate of the line module and terminating at the transceiver inside the line module. Such a connection system is known as an internal connect scheme. Internal connect schemes are difficult to service since the optical fibers were not easily disconnected from their respective optical transceivers. The most common connect scheme is an external connection scheme in which the optical fiber is connected to the transceiver via connection ports on the exterior of the faceplate of the line module. 
   Currently, one of the density limitations on a faceplate mounted cable interconnect scheme is the physical size of the connector. The industry standard as of the filing of this application in the United States is the SC style connector. In Europe, the standard connector in many countries is the FC style connector. Both SC and FC connectors are comparatively large compared to recent connectors developed by Lucent Technologies, specifically the LC connector. As fiber optic interconnect density increases, LC connectors gain in popularity, so much so that many component manufacturers are designing fiber optic transceivers that utilize an integral plastic housing with LC connectors (the female side of the connector is mounted to the transceiver and is accessible from outside the line module). 
   Under an industry multi-source agreement, the small form factor transceiver standard was created and adopted and has been distributed by component manufacturers so that all new small form factor transceivers follow a common package size and interconnect scheme. Many of these new small form factor transceivers are designed with an integral EMI clip that allows the part to be mounted at the front of a given line module (or other circuit pack) and protrude through the front of the equipment faceplate to make cable access easier. 
   Unfortunately, mounting small form factor transceivers on line module faceplates causes the fiber optic cable to enter the faceplate at an angle of incidence such that it becomes difficult to route the fiber away from the source and, at the same time, prevent the telecommunications equipment chassis doors from crushing the fiber optic cable when closed. Additionally, as the density of the cables increases, it becomes increasingly difficult for technicians to service the equipment without disrupting cables adjacent to the cables that need to be serviced. To address this problem, some cable manufacturers have developed custom boots integral with the cable assembly that bend the cable so as to avoid interference with the door of the chassis. However, current industry solutions are designed to exit the small form factor transceiver orthogonal to (i.e., straight out from) the module. These boots can be rotated slightly but will interfere with adjacent boots when the angle becomes too great. 
   One contemporary device has been produced by Siecor Operations. It is a stainless steel clip which fits along the base of the optical fiber and fits under the connector boot of an SC or FC connector. It acts like a spine for the cable, bending it roughly 90°. However, it has several problems associated with it. First, it is completely incompatible with LC connectors that do not have specific Siecor boots attached thereon. Second, it does not actually cover a significant amount of the cable; as a result, even though the cable is kept fairly rigid, the clip does not actually protect the fiber optic cable. A sharp blow by either the door of the chassis of a networking device or by an incautious technician can still damage the optical fiber cable. Finally, there is no way to tell precisely where on the optical fiber this device is supposed to be placed for optimal bending. 
   Another such contemporary device is produced by Corning Cable Systems and is a plastic clip compatible with LC connectors similar to the stainless steel Siecor clip described above. The Corning clip fails to support the bent portion of the fiber throughout the entire section of bent fiber. As such, the fiber may not lay properly in the Corning clip. Also, the Corning clip appears to be less than reliable when used with smaller width optical fibers. Specifically, optical fiber comes in a variety of widths, from 1.6 to 2.0 mm. The Corning clip does not hold fibers in the smaller end of that width range very securely at all. 
   Other similar contemporary fiber bending devices require a stiffening rib to provide support and strength for the fiber bender. These stiffening ribs increase the size of the fiber bender; as a result, adjacent fibers connected to the same LC connector (which typically accommodates two fibers very close together) are pushed apart, causing undue stress on the connector and thus the transceiver. 
   Other companies utilize external faceplate interconnect schemes which cannot utilize the current industry solutions. Moreover, some of the equipment already in the field utilizes LC connectors which are mounted internally to the faceplate where bending the cable is not required. A solution must be available which is compatible with LC connectors and yet removable so that existing networking devices that do not require fiber bending are still serviceable, bearing in mind that optical fibers are brittle and may break during removal, insertion, or servicing of line modules. 
   SUMMARY OF THE INVENTION 
   The invention is a fiber bending apparatus for bending an optical fiber in a networking device. It has an arcuate main body having a first end, a second end, and a central channel. The central channel is preferably disposed along the side of the main body substantially perpendicular to the curvature of the main body (i.e., the fiber bender curves up and away from a module faceplate and the channel is on the left or right side of the bender). The provision of the channel on the side of the bender allows the bender to support the bent fiber throughout the entire length of the bent portion of the fiber. If the channel were disposed on the top of the apparatus along the curvature of the bend of the main body, any fiber disposed therein might not lie flat along the bottom of the channel. However, placing the channel on the side of the apparatus provides support from both above and below the fiber via the walls of the main body. 
   The first end is shaped to receive in the central channel an optical fiber and the second end is shaped to receive in the central channel a connector boot disposed around the optical fiber. The fiber bending apparatus bends a fiber disposed in the central channel away from a chassis of the networking device, and preferably bends the fiber substantially orthogonal to a direction from which the fiber is connected to the line module. The arcuate main body has a radius of curvature substantially equal to the minimum industry-recommended bend radius for optical fiber. In this way, the fiber bender acts to provide as much clearance as possible between the optical fiber emerging from the line module and the chassis. 
   The fiber bending apparatus preferably includes a shoulder formed in the central channel at a predetermined distance from the second end. The shoulder narrows the central channel. When a connector boot is inserted into the second end of the apparatus, the shoulder is engaged by the fiber connector boot to thereby prevent the connector boot from being inserted into the fiber bending apparatus beyond the predetermined distance. In this way, the inventive fiber bender has a depth gauge to prevent the connector boot from being inserted too far into the bender. This feature is important, since should the connector be inserted too far into the bender, two fiber benders on adjacent optical fibers would interfere with each other and push the two optical fibers apart; this would put undue stress on both the optical fibers and the optical transceiver. 
   Preferably, at least the second end of the main body is resilient and forms a friction fit with a connector boot inserted therein. At least one retaining projection is formed in the central channel. Projections formed near the first end engage the optical fiber and help to prevent the fiber bending apparatus from easily falling off of the optical fiber, while projections formed near the second end engage the connector boot and also help to prevent the fiber bending apparatus from easily falling off of the optical fiber. 
   The invention also includes an optical fiber management system. An outer chassis is provided with inner support structure mounted within the chassis. A plurality of line modules are inserted and supported by the support structure, each of the line modules having a plurality of optical transducers connected to female connectors. A plurality of optical fibers each respectively terminating in connector boots and male connectors are matingly engageable with the female connectors. A plurality of fiber bending devices similar to those described above, are selectively attachable to the optical fibers. Each of the fiber bending devices includes an arcuate main body having a first end, a second end, and a central channel. The first end is shaped to receive in the central channel one of the optical fibers and the second end is shaped to receive in the central channel one of the connector boots disposed around the one of the optical fibers. The plurality of fiber bending devices bend the optical fibers away from the chassis substantially orthogonal to a direction from which the optical fibers are connected to the line modules. 
   The invention also includes a method of organizing and managing optical fibers in a networking device utilizing the inventive fiber bender discussed above. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an overall schematic of a telecommunications networking device using the optical fiber management system according to an embodiment of the invention. 
       FIG. 2  is a perspective view of a line module component of the telecommunications device of FIG.  1 . 
       FIG. 3A  is a perspective view of a fiber bender according to an embodiment of the invention. 
       FIG. 3B  is a side elevational view of the fiber bender of  FIG. 3A  with an optical fiber disposed therein. 
       FIG. 4  is a sectional view of the optical fiber management system taken along line  4 — 4  of  FIG. 1  with the connector boots and optical fiber cables not shown for clarity. 
       FIGS. 5A-C  are alternate embodiments of the fiber bender invention which accommodate two adjacent optical fibers. 
       FIG. 5D  is an alternate embodiment of the fiber bender of FIG.  3 A. 
       FIG. 5E  is the embodiment of  FIG. 3A  shown next to  FIGS. 5A-D  for comparative purposes. 
   

   DETAILED DESCRIPTION OF THE EMBODIMENTS 
   Description will now be given of the invention with reference to  FIGS. 1-5E . It should be noted that the figures are exemplary in nature and are meant in no way to limit the scope of the invention. 
     FIG. 1  depicts a schematic of a typical telecommunications networking device  5  usable in an optical network. Device  5  includes a chassis  10  which has an openable door  12  shown in broken view. Within the chassis is disposed some support structure (not shown) such as shelving, hooks, etc., for supporting a series of circuit boards or line modules  14 . Previously, line modules were provided with eight optical transceivers each with their respective optical fibers being mounted internal to the faceplate of the line module (such a device is known as an LM-8). With the advent of the less bulky small form factor transceivers described above, the new standard of line modules is now being provided with sixteen optical transceivers (or an LM-16) in a faceplate mounted external interconnect scheme. 
     FIG. 2  shows in perspective a typical modern line module  14 . It is provided with sixteen female LC connectors  15  mounted on the faceplate  14 A of the line module. Each female LC connector  15  has two receptacles, each one adapted to receive one optical fiber  16  (see  FIG. 1 ) having a corresponding male LC connector (not shown) at its end. Each female LC connector  15  is respectively connected to an optical transceiver  19 . Transceivers  19  are bi-directional; consequently, two optical fibers  16  are required for each transceiver (one for incoming signals and the other for outgoing signals). Line module  14  also includes one or more retaining levers  17  which secure the line module inside chassis  10  of networking device  5 . 
   The device of  FIG. 1  has a number of line modules  14  disposed inside chassis  10 . Each line module requires up to 32 optical fibers  16  to be connected to LC connectors  15 . Should a device  5  have a mere sixteen line modules  14 , the device could require as many as 512 optical fibers  16 . Since the size of the chassis can be constrained by telecommunications industry standards, it is desirable to maintain some semblance of order and organization of the optical fibers which must be routed within a space-constrained chassis. To this end, the chassis is provided with cable routers  18  at the top and/or the bottom (not shown) of the inside of the chassis. As shown in  FIG. 1 , optical fibers  16  are routed in groups around cable routers  18  so as to keep them relatively segregated and orderly. 
   However, cable routers  18  alone are insufficient. Optical fibers  16  from one line module can interfere with those of a neighboring line module. Further, and more importantly, the optical fibers must be made to lie flat and run substantially along the faceplate of their line modules so that a) the closing of the chassis door does not crush and break the optical fibers, and b) a technician may service one line module without damaging or disrupting the optical fibers of an adjacent line module. 
   To address these and other problems, an embodiment of the fiber optic management system includes a fiber bender  20  shown in  FIG. 3 ; in  FIG. 3A , it is shown by itself in perspective, and in  FIG. 3B , it is shown in side elevation with an associated optical fiber. Fiber bender  20  includes an arcuate or horn-shaped main body having a first end  22  and a preferably larger second end  24 . A central channel  23  is formed on the side of the main body and is surrounded by walls  27 ; in such a configuration, the cross-section of the main body is substantially in the shape of the letter “C” or a semi-circle, or similar such geometric shape. The provision of channel  23  on the side of the main body rather than the top of the main body enables fiber bender  20  to support the entire length of the bent portion of the fiber from both sides via walls  27 . In this way, fiber bender  20  serves to maintain the proper bend radius throughout the entire length of the bent portion of the fiber. 
   As shown in  FIG. 3B , the standard optical fiber  16  that is being fitted inside fiber bender  20  consists of the optical fiber cable itself, a connector boot  16 A, and a male LC connector  16 B. Connector  16 B is matingly engageable with female LC connector  15  shown in FIG.  2 . Connector boot  16 A is provided around the fiber cable before it terminates in the male LC connector  16 B to provide strain relief and protection for the cable as it emerges from the rear portion of LC connector  16 B. The first end  22  of fiber bender  20  is adapted (i.e., shaped, dimensioned, designed, etc.) to receive the proximal or non-connector side of optical fiber  16  as shown in FIG.  3 B. Second end  24  is preferably larger in width than first end  22  and is adapted to receive part of connector boot  16 A. It is intended that fiber bender  20  cover part of connector boot  16 A so that the bending of the fiber can begin as close to the connector  16 B as possible, thereby reducing the amount the fiber sticks out perpendicularly from faceplate  14 A. 
   However, it is important that the fiber bender not be fitted around the extreme lowermost portion of connector boot  16 A. As shown in  FIG. 2 , the two female ports of a single LC connector  15  are extremely close together; there is barely enough room for two optical fibers  16  to be connected to the same LC connector  15 . If the fiber benders of the two optical fibers were placed at the lowermost end of their respective connector boots  16 A, the two fiber benders would add significantly to the overall diameter of the optical fibers, and the fibers would push against each other when they were connected to the same connector. This situation is unacceptable as it would produce undesirable stresses on the optical transceiver and the fibers themselves. 
   Consequently, it is important to control the depth to which the connector boots may be disposed inside the channels  23  of fiber benders  20 . Shoulder  26  is formed on the interior of channel  23  so as to narrow the width of the channel. As the optical fiber is threaded into channel  23  and the connector boot  16 A is inserted deeper into the fiber bender, the rear wall  16 A- 1  of connector boot  16 A eventually abuts shoulder  26  and is thereby prevented from travelling further into channel  23 . In this way, the fiber bender  20  is prevented from being placed too far down on the connector boot. Also, shoulder  26  acts as a depth gauge to insure that fiber bender  20  is placed sufficiently close to male LC connector  16 B. One of the functions of fiber bender  20  is to bend the optical fiber away from the chassis door  12  so that the fiber will not stick out too far from faceplate  14 A and thus be crushed when the door is closed. Fiber bender  20  minimizes the profile of the optical fiber. If fiber bender  20  is placed too high on the optical fiber (i.e., too far away from the connector end of the fiber), then the profile of the fiber may not be reduced sufficiently to avoid a closing chassis door. By inserting the connector boot  16 A until it abuts shoulder  26 , the profile of the optical fiber is sufficiently reduced in an easily repeatable manner. 
   Fiber bender  20  is an arc-shaped device that subtends an angle □ as shown in FIG.  3 B. Since the optical fiber initially emerges from faceplate  14 A perpendicular to faceplate  14 A, and since it is desired to bend the fiber to be parallel to faceplate  14 A, it is preferred that the fiber bender bend the fiber approximately 90°. It is borne in mind by the inventors that optical fiber, a standard article of commerce, has an industry-recommended minimum bend radius which is set to avoid breaking the optical fiber. As such, one skilled in the art will be cognizant of this minimum bend radius and will appreciate that the inventive fiber bender  20  is dimensioned so as not to bend an optical fiber any smaller than the industry-recommended bend radius. 
   In addition, bender  20  is provided with one or more projections  28 , preferably along the tops of walls  27 . These projections engage the cable or the connector boot (depending upon where the projections are formed on the bender) and help prevent the optical fiber from falling out of central channel  23 . 
   The main body of fiber bender  20  is preferably made from a resilient material such as metal, plastic, or a similar material. The material is sufficiently stiff to withstand inadvertent impacts by technicians, however at least the second end  24  of the bender is resilient so that the connector boot of the optical fiber can be friction fitted therein. 
   The overall inventive fiber management system can be seen in  FIGS. 1 and 4 . In  FIG. 1 , it is shown that some of the fibers  16  may be routed vertically upwards and that some of the fibers  16  may be routed vertically downwards.  FIG. 4  demonstrates the flexibility of the inventive system (connector boots and the fibers themselves are not shown for clarity).  FIG. 4  is a sectional view of the overall system of  FIG. 1  taken along line IV—IV. As shown in  FIG. 4 , fiber benders  20  are disposed a predetermined distance from the faceplate  14 A of line module  14 , owing to connector boot  16 A abutting shoulder  26  of the fiber bender. 
   It should be noted that every other fiber bender in  FIG. 4  can be rotated slightly off the exact straight vertical line of line IV—IV (in  FIG. 4 , it is the lower fiber bender of each pair; of course, it could just as easily be the upper fiber bender). If the fibers were all aligned precisely vertically, the lower fiber of each pair of fibers would be overlapping its upper fiber neighbor. Such a configuration may be undesirable, as the overall profile of the fibers is increased and the chassis door may impact on the overlapping fiber. Also, by bending the lower fiber with the fiber bender and then bending the lower bent fiber over the upper bent fiber, undue stress may be created in the lower fiber. Consequently, the lower fiber is preferably rotated slightly off the vertical so as to avoid interfering with its neighboring fiber. The provision of channel  23  on the side of the main body of the fiber bender makes this rotation extremely easy. Providing channel  23  on the side rather than the top also insures that any inadvertent impacts with the optical fiber will strike the fiber bender and not the fiber itself; if the channel were formed in the top part of the main body, the fiber may be exposed to damaging impacts. 
   Alternate embodiments of the inventive fiber bender are shown in  FIGS. 5A-D . Fiber benders  120 ,  220 , and  320  differ slightly from the first embodiment of the bender  20  in that they accommodate both optical fibers for a given two-port LC connector. Thus, as shown in  FIG. 5A , bender  120  has a first end  122  for receiving two optical fiber cables, and second end  124  is adapted to receive two connector boots  16 A. Central channel  123  is wide enough to accommodate two fibers  16 . At least one fin  125  may be provided to give bender  120  sufficient stiffness. Transverse stopper  126  prevents the connector boots from being inserted too far into bender  120  while providing lateral support for the bender. Projections  128  function similarly to projections  28  of the embodiment described in FIG.  3 . 
     FIG. 5B  depicts another alternate embodiment of the fiber bender. Bender  220  is also a two-fiber bender, having first end  222  and second end  224  as before. A central divider  221  is provided in channel  223  to keep the two optical fibers disposed in channel  223  reasonably apart from one another. Walls  227  come up much higher over central channel  223  so that they effectively act as projections which retain the optical fibers inside channel  223 . A support rib  225  is provided for rigidity. 
   Bender  320  of  FIG. 5C  is similar to bender  120  of  FIG. 5A  with some slight modifications. Central divider  321  is provided at second end  324  to keep the connector boots properly spaced apart, while central divider post  321 A is provided at first end  321  to separate the optical fiber cables. Support rib  325  is provided similar to rib  225  of FIG.  5 B. Walls  327  and projections  328  are provided similar to walls  127  and projections  128  of FIG.  5 A. Transverse rib  326  provides lateral support for the bender and allows the plastic injection mold tool to be simpler and more cost effective. 
     FIG. 5D  shows a single fiber bender  420  which is similar in many respects to bender  20  of FIG.  3 . The various parts of  FIG. 5D  correspond to those referenced in  FIG. 3  but with reference numerals in the  400 s; e.g., ends  422  and  424  are substantially similar to ends  22  and  24  of  FIG. 3 , channel  423  and shoulder  426  are similar to channel  23  and shoulder  26  of  FIG. 3 , and walls  427  and projections  428  are similar to walls  27  and  28 . Fiber bender  420  adds core cuts  429  (removed material) in channel  423  below projections  428 . The provision of core cuts  429  serves to facilitate tooling and injection molding. 
   The invention is not limited to the above description but rather is defined by the claims appearing hereinbelow. Modifications to the above description that include that which is known in the art are well within the scope of the contemplated invention.