Abstract:
A jumper cable module for use, e.g., with optical and/or electrical equipment. The module provides proper tensioning for jumper cables and retains them in a protected manner. In one embodiment, the module includes a pulley and an eccentric cam pivotally connected to a base plate. A jumper cable is wrapped around grooves in the pulley and cam such that the connectorized ends of the cable extend out and attach to the specified connection points. The cam is turned about its axle to produce the desired tension of the cable. For maintaining the tension, the cam may incorporate a tensioning mechanism, e.g., a spring-loaded ball mechanism or serrated edge ratchet. When the cable needs to be removed from the module, the tensioning mechanism is disengaged and the cam is turned to create slack in the cable for ease of cable removal. A module that includes stacks of pulleys and cams may handle multiple jumper cables. Certain modules of the present invention reduce damage to and improve handling of fiber optic jumper cables during installation and maintenance of optical communication equipment.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to electrical and optical equipment. 
     2. Description of the Related Art 
     Voice and data communications equipment is often designed such that printed circuit boards fitted with faceplates are inserted side-by-side into card cages. Connectorized assemblies (e.g., fiber optic jumper cables terminated at each end with a connector) are used to transmit (optical) signals from point to point within the card cage, e.g., from the circuit board to the faceplate, between two points within the same circuit board, between two different circuit boards, etc. Typically, four to eight fiber optic jumper cables may be used per circuit board in a cage. In some instances, an even greater number of jumper cables per circuit board may be required. Additional fiber optic jumper cables may also be needed for connections between different card cages, cabinets, or shelves. 
     Under current practice, two ends of a fiber optic jumper cable are connectorized and manually attached to the specified points, e.g., to the circuit board and faceplate. The amount of slack in the fiber between the points of attachment may vary depending on the distance between those points, length of the jumper cable, and other geometrical or topological constraints. In addition, jumper cables are often intentionally made longer than would be necessary to make the specified connections in order to have an extra length of fiber for repairs, such as replacement of broken connectors or removal of damaged sections of fiber. For these reasons, fiber optic jumper cables often end up dangling, jutting out, or otherwise protruding, e.g., from the surface of the circuit board. 
     During installation and/or maintenance, circuit boards are usually inserted into and/or pulled out of the card cage. An often occurring problem is that a dangling or protruding fiber optic jumper cable is damaged when it catches an obstacle, e.g., a piece of equipment within the cage, constriction of the card slot, or another jumper cable protruding from a different circuit board. Repair and replacement of the damaged fiber optic jumper cables may add significantly to the operational cost of telecommunication equipment. 
     SUMMARY OF THE INVENTION 
     In one embodiment, the present invention provides a jumper cable module for use with communication equipment. The module provides proper tensioning for jumper cables and retains them in a protected manner. The module includes a pulley and an eccentric cam pivotally connected to a base plate. A jumper cable is wrapped around grooves in the pulley and cam such that the connectorized ends of the cable extend out and attach to particular connection points (e.g., on the same or on two different circuit boards). The cam is turned about its axle to produce the desired tension of the cable. For maintaining the tension, the cam may incorporate a tensioning mechanism, e.g., a spring-loaded ball mechanism or a serrated edge ratchet. When the cable needs to be removed from the module, the tensioning mechanism is disengaged and the cam is turned to create slack in the cable for ease of cable removal. A module that includes stacks of pulleys and cams may handle multiple jumper cables. The present invention can be used to reduce damage to and improve handling of jumper cables during installation and maintenance of communication equipment. 
     According to one embodiment, the present invention is a jumper cable module, comprising: (a) a pulley connected to a base plate; and (b) a cam pivotally connected to said base plate, wherein: the jumper cable module is configured to provide tensioning to a jumper cable (i) placed within the jumper cable module and (ii) connected to connection points, which tensioning is achieved by rotating the cam to a selected angular position. 
     According to another embodiment, the present invention is a method of tensioning a jumper cable connected to connection points, the method comprising the steps of: (a) placing the jumper cable within a jumper module, wherein the jumper cable module comprises a pulley connected to a base plate and a cam pivotally connected to said base plate; and (b) rotating the cam to a selected angular position to achieve desired tension in the jumper cable. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other aspects, features, and advantages of the present invention will become more fully apparent from the following detailed description, the appended claims, and the accompanying drawings in which: 
     FIG. 1A is a perspective view of a fiber optic jumper module according to one embodiment of the present invention; 
     FIG. 1B is a top view of the fiber optic jumper module of FIG. 1A illustrating the use of the module with fiber optic jumper cables of two different lengths; 
     FIG. 2 is a perspective view of a fiber optic jumper module according to another embodiment of the present invention; 
     FIG. 3 is a perspective view of a fiber optic jumper module according to yet another embodiment of the present invention; 
     FIG. 4 is a side view of the fiber optic jumper module shown in FIG. 3; 
     FIG. 5 is a top view of part of the tensioning mechanism of the fiber optic jumper module shown in FIG. 3; and 
     FIG. 6 is a perspective view of a fiber optic jumper module according to still another embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION 
     Reference herein to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the invention. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Although the invention is particularly suitable for use with circuit boards and fiber optic jumper cables those skilled in the art can appreciate that the invention can be equally applied to other types of electrical or optical equipment and/or other types of cable, including electrical cables/wiring. 
     FIG. 1A shows a perspective view of a fiber optic jumper module  100  according to one embodiment of the present invention. Module  100  comprises a pulley  102  and an eccentric cam  104 . Both pulley  102  and cam  104  are connected to a base plate  106 . In one embodiment, base plate  106  may be part of a circuit board. In different embodiments, base plate  106  may be a separate board in a card cage or part of module  100 . Pulley  102  may have an optional axle  108  configured to rotatably connect pulley  102  to base plate  106 . In an embodiment that does not include axle  108 , pulley  102  may be fixedly attached to base plate  106 . Cam  104  is pivotally connected to base plate  106  using an off-center axle  110 . Cam  104  may also have an optional ear  116  that can be grasped for turning cam  104  about axle  110 . Along their respective perimeters, both pulley  102  and cam  104  incorporate grooves  112  and  114 , in which a fiber optic jumper cable  118  can be placed. Cable  118  typically includes connectors  120  that may be connected to particular connection points, e.g., on a circuit board or faceplate. 
     FIG. 1B shows a top view of module  100  and demonstrates the principles of using the module with fiber optic jumper cables of varying lengths. Illustratively, the operation of module  100  with a relatively long cable  118   a  and a relatively short cable  118   b  is shown. The following representative steps may be used to engage module  100 . Cable  118   a  or  118   b  is connected to a first connection point using one connector  120 . The cable is then placed within groove  112  of pulley  102  and optionally wrapped around the pulley within the groove one or more times. With cam  104  oriented at position C, the cable is then placed within groove  114  of cam  104  and connected to a second connection point using the other connector  120 . To remove any unwanted slack, cam  104  is then rotated (clockwise in FIG. 1B) about axle  110  to produce the desired tension in the cable. For example, for the relatively long cable  118   a , cam  104  is rotated clockwise from position C to position A and fixed in position A. Similarly, for the relatively short cable  118   b , cam  104  is rotated clockwise from position C to position B and fixed in position B shown by the dashed line in FIG.  1 B. For fixing the cam in a desired position, e.g., positions A or B, and maintaining the desired tension of the cable, cam  104  may incorporate a tensioning mechanism, possible embodiments of which are disclosed below in the context of FIGS. 5 and 6. Subsequently, if cable  118  needs to be removed from module  100 , the tensioning mechanism is disengaged and cam  104  is turned back toward position C (e.g., counterclockwise in FIG. 1B) to create slack in the cable for ease of cable removal from groove  114  of cam  104  and/or groove  112  of pulley  102 . 
     In one embodiment, pulley  102  is a grooved disk having a radius of R 1 , where R 1  is preferably larger than the greater of the acceptable bend radius of cable  118  (defined as the bend radius at which leakage of light from the optical fiber in the cable due to its curvature exceeds a predetermined level) and the critical bend radius of cable  118  (defined as the radius at which the optical fiber in the cable breaks). Cam  104  is a grooved plate, e.g., having the shape of a rectangle with rounded corners. Similar to pulley  102 , the rounding radius R 2  of the cam is chosen based on the acceptable and critical bend radii of cable  118 . Depending on the implementation, R 1  may equal R 2 . Furthermore, different shapes, e.g., a bar, an oval, or a rounded triangle, may be utilized for pulley  102  and/or cam  104 . In addition, axle  110  may be centrally located on cam  104 . 
     FIG. 2 shows a perspective view of a fiber optic jumper module  200  according to another embodiment of the present invention. Module  200  comprises a stack  202  of pulleys  102  and a corresponding stack  204  of eccentric cams  104 . In one embodiment, stack  202  includes four pulleys  102  and stack  204  includes four cams  104 . Each individual cam  104  of stack  204  can swivel around axle  210  independently of the other cams in the stack. Also, each cam  104  of stack  204  can independently be fixed in a desired position using its individual tensioning mechanism. 
     In operation of module  200 , a fiber optic jumper cable is wrapped around a pulley  102  of stack  202  and inserted into the groove of the corresponding cam  104  of stack  204 , which cam and pulley are preferably located at the same vertical position in their respective stacks. Then, the cam is rotated and fixed as described above to produce the desired tension on the cable. This procedure may be repeated for each corresponding pulley/cam pair for a different fiber optic jumper cable. In the embodiment shown in FIG. 2, module  200  can accommodate up to four different cables. In different embodiments, stacks  202  and  204  may have more or fewer than four pulleys and cams, respectively, and accommodate a corresponding number of different cables. 
     FIG. 3 shows a perspective view of a fiber optic jumper module  300  according to yet another embodiment of the present invention. Module  300  comprises a stack  302  of four pulleys and a stack  304  of four cams. Therefore, similar to module  200  of FIG. 2, module  300  can accommodate up to four fiber optic jumper cables. However, a different structure for the stack of cams (stack  304 ) is used in module  300  compared to that (stack  204 ) in module  200 . Similar to stack  204 , stack  304  includes four cams  104 . Only one cam  104  of stack  304  is illustrated in FIG. 3 (see dashed line). The other cams  104  are not visible in the view presented in FIG. 3 except for their ears  116 . In addition to four cams  104 , stack  304  also includes four round plates  305 , three of which are inserted between cams  104  and the fourth one is placed on top of the topmost cam  104 . In a preferred embodiment, each plate  305  is attached to cam  104  located beneath that plate such that the center of plate  305  corresponds to the pivoting point of cam  104 . Each cam/plate pair is rotatably connected to base plate  306  by an axle  310  of stack  304 . Plates  305  in module  300  serve the purpose of reducing the exposed length of cable within the module. In particular, plates  305  enclose and protect from possible damage at least part of the length of cable corresponding to sections DE and FG of cable  118   a  of FIG.  1 B. 
     FIG. 4 shows a side view of module  300 . Stacks  302  and  304  are pivotally connected to a base plate  306  using axles  308  and  310 , respectively. Module  300  may be attached to a board  322 , which can be, e.g., a circuit board, using spring-loaded legs  324 . In one embodiment, module  300  has two legs  324  located beneath the pivot points of stacks  302  and  304 . In different embodiments, one, three, or more legs  324  located at different points may be used. Each leg  324  has an elastic compressible head  326  and a spring  328 . To attach module  300  to board  322 , head  326  is squeezed and pushed though a round opening in board  322 , which opening preferably has a diameter slightly smaller than that of head  326 . After protruding through the opening, head  326  expands and locks spring  328  in a partially compressed state between base plate  306  and board  322 . The expansion force of spring  328  provides support for module  300 . 
     FIG. 5 shows a top view of a tensioning mechanism  330  of module  300 , also shown in FIG.  3 . Mechanism  330  comprises sixteen nested holes  502  in each plate  305  of stack  304 , sixteen matching nested holes in each cam  104  of stack  304 , and sixteen matching nested holes in base plate  306 . The nested holes are arranged in a circle around axle  310  as shown in FIG.  5 . Mechanism  330  further comprises at least four pairs of spring-loaded balls (not shown). At least one pair of spring-loaded balls is inserted between each cam  104  and plate  305  located beneath that cam such that the balls are nested in the matching holes. For the bottom-most cam  104 , at least one pair of spring-loaded balls is inserted in a similar fashion between that cam and base plate  306 . 
     In operation, tensioning mechanism  330  can fix each cam  104  of module  300  in sixteen different angular positions using the locking action of a spring-loaded ball settled into one of the sixteen nested holes of that cam. To change the angular position of cam  104 , that cam is rotated such that the spring-loaded ball skips and settles into a different nested hole. For the particular embodiment of mechanism  330  shown in FIG. 5, the angular position of each cam  104  in stack  304  can be changed with increments corresponding to about 22.5 degrees (i.e., {fraction (1/16)}-th of a full turn). In different embodiments of mechanism  330 , different increments may be implemented using a different number of nested holes. 
     FIG. 6 shows a perspective view of a fiber optic jumper module  600  according to still another embodiment of the present invention. Module  600  is similar to module  300  of FIG.  3 . However, one difference between these two modules is that stacks  602  and  604  of module  600  include eight pulleys and cams compared to four pulleys/cams in stacks  302  and  304  of module  300 . Therefore, module  600  can accommodate up to eight fiber optic jumper cables compared to four cables for module  300 . Another difference between these two modules is the tensioning mechanism. Module  600  has a serrated edge ratchet, well known in the art, instead of mechanism  330  for module  300 . In different embodiments, other designs of tensioning mechanisms, such as button stopper, coil, or friction stopper arrangements, can also be applied. In general, any suitable tensioning mechanisms that can fix an individual cam in a desired position and maintain proper tension of a jumper cable may be used with jumper cable modules of the present invention. 
     Modules  100 ,  200 ,  300 , and  600  may be loaded with fiber optic jumper cables at the point of manufacture, by a third party, or at the point of installation onto a circuit board. A module can be part of a circuit board or a separate unit inserted into its own slot in a card cage. An operator or a robot may install the module onto a board, card cage, shelf, or cabinet. A jumper cable module of variable capacity can be implemented using a modular approach. In such a module, pulleys and cams are added/subtracted from the corresponding stacks as needed to increase/decrease capacity of the module. Various materials and methods of manufacture may be employed in producing the modules. For example, the modules may be made of plastic and produced using injection molding. 
     While this invention has been described with reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications of the described embodiments, as well as other embodiments of the invention, which are apparent to persons skilled in the art to which the invention pertains are deemed to lie within the principle and scope of the invention as expressed in the following claims.