Abstract:
A guide for affixing to a panel to limit the bend radius of fiber optic cable. The guide is adapted for placement at a hole through the panel to limit the bend radius of cable routed through the hole, or alternately, for placement on the panel for guiding cable that is routed parallel to the panel while limiting the bend radius of the cable. The guide is further adapted to provide a storage spool for excess cable.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention is related to the protection and guidance of optical fiber cables. More specifically, the invention is a device for retaining the bend of one or more optical fiber cables at a safely large radius while guiding them through a hole in a panel, while routing them along the surface of a panel, or while storing them on a panel. It has a particular application in the telecommunications industry.  
         BACKGROUND OF THE INVENTION  
         [0002]    Fiber optic cables that are routed to and within equipment must be protected from being bent too sharply as might occur at sharp corners and edges or when excess cable is hanked for storage. Such sharp bending can cause cable fibers to be physically damaged by overstressing, and can cause functional failure of the fibers by changing internal optical properties at those bends. Specifically, loss of proper internal reflection of light traveling through the fiber as it reaches the overly sharp bend will be realized. It is therefore advantageous to keep a cable from being bent below its minimum bend radius even temporarily while installing and storing cable, and to provide some physical support to limit the bend radius during use.  
           [0003]    One common method to avoid sharp bends is to spirally wrap cables around cylindrical tubing of a sufficient outside diameter, which tubing is then routed along the intended path of the optical cable. Although this method does ensure that the cable bend will never be sharper than the tubing&#39;s outside diameter, installing the tubing with the spirally wrapped cable is a tedious process. It is also expensive to tubing along the entire length of the cable&#39;s pathway just to ensure a sufficient radius only at the bend locations.  
           [0004]    Some devices that support cable around curved surfaces only locally at the bend locations are known and include, for example, those shown in U.S. Pat. Nos. D427,897; 5,530,787; 5,724,469; 5,917,982; 5,937,131; 5,946,440; 5,995,699; 6,002,089; and 6,049,040. Such devices can be attached to panels along the intended route of the trays, but are only designed to address guiding of cable along its route or the storage of excess cable in a hank. It is therefore desirable to provide a singular device for retaining the bend of one or more optical fiber cables at a safely large radius either while guiding them through a hole in a panel, while routing them along the surface of a panel, or while storing them on a panel.  
           [0005]    An additional problem faced when routing fiber optic cables through holes in panels is that the edges of such holes are often sharp or jagged. These edges can cause damage to or cut through the cable. It is therefore desirable to provide a means for protecting the cable from contact with the hole edge.  
         SUMMARY AND OBJECTS OF THE INVENTION  
         [0006]    The present invention is a device for fixing to a panel or such and having a curved surface with a radius of curvature that is larger than the specified minimum bend radius for fiber optic cable. The device is adapted to support cables as they meander between and within equipment, whether on or through panel surfaces, while retaining the bend of the cables at a safely large radius.  
           [0007]    In addition to including means for being affixed to the panel, the invention further includes means for covering the hole&#39;s edge. This is particularly useful in that it protects the cable from the usually sharp hole edge while guiding the cable through the hole.  
           [0008]    The device is also adapted for providing a spool for storing excess cable, when four of the devices are provided and affixed to the panel, arranged in rectangular fashion. This ensures that the stored coil of excess cable cannot be bent sharper than the specified minimum bend radius for the cable.  
           [0009]    Additionally, the invention is adapted to grasp the edges of panel holes and to grasp certain walls protruding from panels so that fasteners are not required. This feature allows for easier, faster, and more reliable assembly to the panel while reducing part count in most cases.  
           [0010]    It is therefore an object of the present invention to provide an improved device for protecting, supporting and guiding fiber optic cable.  
           [0011]    It is a further object to provide such a device which supports cable as it runs along panel surfaces and through panel holes.  
           [0012]    It is a further object to provide such a device that is adaptable to form a cable storage spool.  
           [0013]    It is a further object to provide such a device that protects cable that is routed through sharp edged panel holes from those sharp edges.  
           [0014]    It is a further object to provide such a device that can be affixed to panels and panel holes without auxiliary fasteners.  
           [0015]    Further objects and advantages of the present invention will become apparent upon review of the following description of the preferred embodiment and accompanying drawings thereof. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    These and other objects and features of the invention will become more apparent upon a perusal of the following description taken in conjunction with the accompanying drawings wherein:  
         [0017]    [0017]FIG. 1 is a perspective view of a guide according to the preferred embodiment of the invention;  
         [0018]    [0018]FIG. 2 is a side view of the guide of FIG. 1;  
         [0019]    [0019]FIG. 3 is a top view of the guide of FIG. 1;  
         [0020]    [0020]FIG. 4 is an end view of the guide of FIG. 1;  
         [0021]    [0021]FIG. 5 is a cross-sectional side view of the guide of FIG. 1 shown affixed by means of the clip to a panel hole;  
         [0022]    [0022]FIG. 6 is a perspective view of a guide of FIG. 1 shown affixed by means of the clip to a flange which protrudes from a panel;  
         [0023]    [0023]FIG. 7 is an exploded perspective view of the guide of FIG. 1 being attached to a panel by screws;  
         [0024]    [0024]FIG. 8 is a perspective view of the guide of FIG. 1 attached to a panel hole and supporting several cables that are routed through the hole;  
         [0025]    [0025]FIG. 9 is a perspective view of the guide of FIG. 1, attached to a panel tab and supporting several cables that are routed along the panel;  
         [0026]    [0026]FIG. 10 is a perspective view of a group of four of the guides of FIG. 1 arranged to form a cable storage spool and supporting a coil of stored cable;  
         [0027]    [0027]FIG. 11 is a perspective view of a guide according to a secondary embodiment of the invention;  
         [0028]    [0028]FIG. 12 is a side view of the guide of FIG. 11;  
         [0029]    [0029]FIG. 13 is a top view of the guide of FIG. 11;  
         [0030]    [0030]FIG. 14 is an end view of the guide of FIG. 11; and  
         [0031]    [0031]FIG. 15 is a perspective view of a pair of the guides of FIG. 11 arranged to form a cable storage spool and supporting a coil of stored cable. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0032]    An optical fiber cable guide  100  according to the preferred embodiment of the present invention is depicted in FIGS. 1 through 7 and described herein. The guide is a singular component integrally molded of polycarbonate or an equivalent material.  
         [0033]    Quarter-cylindrically curved guide surface  101  has a radius of curvature of one inch. This radius is sufficiently large to that fiber optic cables are not bent too sharply when supported there-around as in FIGS. 8 through 10. The quarter-cylinder of the guide surface is terminated at both ends by end walls  103 , which extend inwardly towards the cylinder&#39;s imaginary axis and extend radially beyond the cylinder to provide arcuate flanges  104  that serve to retain the cable on the guide surface. Two slots  105  pass through the guide surface, each toward an opposite end thereof, through which a tie wrap or such (not shown) can be passed to secure cable against the guide surface.  
         [0034]    The end walls include screw slots  107 . Front wall  108  extends longitudinally and connects the cylinder axis to the guide surface. The cylindrical curve of the guide surface and the arcuate flanges of the end cap extend beyond the front wall to form a protective lip  109  that runs longitudinally for the length of the guide.  
         [0035]    A slot  112  is molded through the cylindrical guide surface and is centrally positioned longitudinally and co-planar with the front wall. This slot is large enough to allow a clip  113 , preferably made of steel, to pass therethrough and grasp the front wall at its upper edge  114 .  
         [0036]    The clip is a U-shaped spring with a lead-in tip  115  that causes the clip to spread as it is forced over the front wall edge so that the clip grasps the front wall firmly. The resiliency of the steel spring allows the clip to be spread a bit further apart without yielding, as required for the clip to grasp the edge of a panel hole as in FIG. 5 or a panel tab as in FIG. 6.  
         [0037]    The guide is offered in several models, each identical except that the length of the guide surface in each has a different length to support a different number of cables.  
         [0038]    In FIG. 5, a sheet metal panel  116  is provided through which a rectangular hole  117  has been punched. The length and height of the hole are large enough to allow the guide&#39;s protective lip and the clip to pass therethrough. Then, the guide is lowered while the clip&#39;s lead-in engages the hole edge and causes the clip to spread over the edge. The guide is further lowered until the inside  118  of the guide&#39;s cylindrical surface rests on the lowermost edge  119  of the hole and the clip grasps that edge firmly to secure the guide to the panel. The spring characteristics of the clip are optimized for maximum holding force without yielding when the clip is spread to this condition.  
         [0039]    As shown in FIG. 8, cables  121 , having a specified minimum bend radius of less than one inch, are routed from below the hole. They cannot be bent so sharply as they are routed into and through the hole as to damage them or their optical performance, because the curvature of the cylindrical guide surface defines the sharpest bend radius possible for the guide to be larger than the cable&#39;s minimum bend radius. Further, the protective lip of the guide extends over the sharp hole edge and protects the cable from being frayed or cut.  
         [0040]    In FIG. 6, a sheet metal panel  124  is provided from which tab  125  has been punched and bent so as to lie on a plane perpendicular to the surface of the panel.  
         [0041]    The clip is lowered over the upper edge  127  of the tab and grasps the tab firmly. Now, as shown in FIG. 9, cables  128  are routed from below the guide and passed over and supported by the guide in a way that ensures that they cannot be bent so sharply as to damage them or their optical performance for the same aforementioned reason.  
         [0042]    [0042]FIG. 7 depicts an alternate mode of attaching the guide to a panel by screws  130 , when the punching and bending of a tab is not practical.  
         [0043]    In FIG. 10, four of the guides are arranged to form a cable storage spool with each guide being secured to a panel  132  with the screws as in FIG. 7. Surplus cable  131  is then coiled around the spool to ensure an adequate coil bend radius is maintained.  
         [0044]    A secondary embodiment  200  of the invention is depicted in FIGS. 11 through 15. This embodiment is only intended for mounting on a panel with screws as was the first embodiment shown in FIG. 7, and to support cables that are routed along the panel surface. Alternately, it is used in combination with another of the same to form a spool for storage of excess cable  231 , similar to the use of the first embodiment depicted in FIG. 10.  
         [0045]    It should be appreciated by those skilled in the art that the disclosed is simply the preferred of many possible embodiments of the invention, and therefore, the scope of the invention should only be limited by the following claims.