Abstract:
A guide for inserting the prepared end of a coaxial cable into the cylindrical post of an end connector of a coaxial cable. The guide is an elongated member that is fabricated of a resilient material having a plurality flat sides that come together at equal angles to form a number of corners. The bisectors of the corner angles all cross at the central axis of the guide with the length of each bisector between the center axis and the corner being substantially equal to or greater than the inside radius of the post. A central slot passes axially through the guide and a slit passes radially through one side wall of the guide to form an entrance that opens into the slot.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     This invention relates to a guide for directing the prepared end of a coaxial cable into the tubular post of an end connector.  
         [0002]     The guide of the present invention is ideally suited for guiding the prepared end of a coaxial cable into the post of a compression type end connector. The coaxial cable comprises a center conductor surrounded by a dielectric layer which is covered by a metal sheath and an outer protective jacket. A compression type end connector is described in further detail in U.S. Pat. No. 5,470,257, wherein a hollow post is contained within the body of the end connector and is surrounded by a collapsible ring which extends the length of the connector. The extended length makes proper insertion of the center conductor of the cable into the post difficult and awkward and can result in the cable and the post becoming misaligned or damaged.  
         [0003]     A guide for aiding in the insertion of the prepared end of a coaxial cable into the tubular post of an end connector is disclosed in U.S. Pat. No. 6,352,448 to Holliday and Wong. The guide has an elongated cylindrical body and contains a circular bore that passes axially through the body. The exposed center conductor at the prepared end of a coaxial cable is inserted into the circular bore of the guide and the leading edge of the guide is inserted into the hollow post. The guide is dimensional so that the center conductor and the inner dielectric layer surrounding the center conductor will pass into the hollow post, while the wire mesh layer that surrounds the dielectric layer and the outer barrier layer of the cable pass over the outer surface of the post. As can be seen, to obtain this close alignment between the guide and the post, tight tolerances must be maintained between the outer diameter of the guide and the interior of the post. In the event the guide becomes slightly out of line or out of tolerance, the cylindrical guide will bind, or even plug, against the cylindrical inner wall of the post as the guide is passing through the post. This can cause damage to the cable and the post during the extraction process.  
       SUMMARY OF THE INVENTION  
       [0004]     It is a primary object of the present invention to improve guides for inserting the prepared end of a coaxial cable into a cylindrical post of an end connector.  
         [0005]     It is a further object of the present invention to reduce the contact area of a guide that is used to insert the prepared end of a coaxial cable into a cylindrical post of a compression type end connector.  
         [0006]     Another object of the present invention is to provide a guide for inserting the prepared end of a coaxial cable into the post of an end connector that can be easily collapsed to gain easy entry of the guide into the post, yet have sufficient resiliency to support the cable centered in the post when the collapsing force is released.  
         [0007]     Another object of the present invention is to prevent the inner dielectric layer and center connector at the prepared end of a coaxial cable from being damaged as the prepared end of the cable is being inserted into the post of an end connector.  
         [0008]     These and other objects of the present invention are attained by a guide for directing the prepared end of a coaxial cable into a cylindrical post of an end connector. The guide contains a plurality of planar walls that come together to form a series of corners equal in number to the number of walls with the angles subtended by each corner being equal. The bisectors of the corners cross at the central axis of the guide with the length of each bisector from the axis to the corner being about equal to or slightly greater than the inside radius of the post. The guide contains an axially extended slit that provides a passage that opens into a centrally located slot. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]     For a better understanding of these and other objects of the invention, reference will be made to the following detailed description of the invention, which is to be made in association with the accompanying drawings, wherein:  
         [0010]      FIG. 1  is an exploded view showing the prepared end of a coaxial cable and a compression type end connector prior to the end connector being joined to the prepared end of the cable;  
         [0011]      FIG. 2  is a perspective view illustrating the end connector assembly with a guide for locating the prepared end of a cable partially inserted within the assembly;  
         [0012]      FIG. 3  is a perspective view illustrating a first embodiment of the invention showing the prepared end of a coaxial cable radially entering the guide;  
         [0013]      FIG. 4  is an enlarged sectional view taken along lines  44  in  FIG. 2  showing a guide positioned within the post of the end connector;  
         [0014]      FIG. 5  is a perspective view illustrating a second embodiment of the invention;  
         [0015]      FIG. 6  is a perspective view illustrating a third embodiment of the invention;  
         [0016]      FIG. 7  is a perspective view illustrating a fourth embodiment of the invention;  
         [0017]      FIG. 8  is a perspective view illustrating a fifth embodiment of the invention;  
         [0018]      FIG. 9  is a perspective view illustrating a sixth embodiment of the invention;  
         [0019]      FIG. 10  is a perspective view illustrating a seventh embodiment of the invention; and  
         [0020]      FIGS. 11 and 12  further illustrate the manner in which the prepared end of a coaxial cable is mounted within the guide. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0021]     Referring initially to  FIGS. 1-4 , there is illustrated a coaxial cable connector  10  for receiving the prepared end of a coaxial cable  12  therein so that the coaxial cable can be accurately joined to the end connector. The cable connector includes a connector body  13  that contains a hollow, cylindrical post  15 . An internally threaded nut  16  is rotatably secured to the extended end of the post. The post and the body of the end connector are both coaxially aligned along the central axis  17  of the end connector. A compression ring  18  is passed into the back end of the body. The internal surface of the compression ring has an inclined section  19  ( FIG. 2 ) that is arranged to ride in contact against the outside surface of the coaxial cable.  
         [0022]     As illustrated in  FIG. 1 , one end of the coaxial cable  12  is prepared by stripping away part of the outer protective jacket  27  from the end face of the inner dielectric layer  25 . The wire mesh cover  28  that separates the outer protective jacket  27  from the inner dielectric layer is passed back over the protective jacket.  
         [0023]     The outer diameter of the inner dielectric layer is about equal to the inside diameter of the end connector post so that the inner dielectric layer can be slidably received within the post. As the cable moves into the post, the external surface of the post passes between the wire mesh layer and the inner dielectric layer of the coaxial cable. Proper insertion of the prepared cable in the converter results in the center conductor being centrally positioned inside the threaded nut of the end connector. With the center connector properly positioned within the nut, an axially-directed force is applied to the compression ring to drive the inclined section of the ring into the post. This, in turn, compresses the outer protective jacket of the coaxial cable downwardly in a radial direction into frictional engagement with the post thus joining the cable to the end connector with the center conductor  20  in axial alignment with the central axis  17  of the end connector.  
         [0024]     Over time, and particularly with the advent of compression type end connectors, the end connectors have increased considerably in length. As a consequence, the receiving end of the connector post is typically well hidden inside the body of the connector making accurate insertion of the prepared end of the coaxial cable difficult. As noted above, misalignment of the cable during insertion can lead to the center conductor becoming bent or even broken and the inner dielectric layer of the cable becoming damaged. A solution to this problem is the use of elongated cylindrical guides to help locate the prepared end of a coaxial cable within the post of a coaxial connector. These efforts have met with only limited success.  
         [0025]     The prior art shows the use of a loose fitting cylindrical guides fitted within the post (U.S. Pat. No. 6,352,448). Attempting to pass a close fitting cylindrical guide through a tubular post can pose problems particularly as the depth of penetration of the guide lengthens. Any slight variations in the clearance between the two mated parts can cause the guide to become misaligned or even plugged within the post. The prior art cylindrical guides generally have an oversized axially disposed bore that passes inwardly through one of the guide end faces for housing the exposed center conductor of the cable that is being guided into the post. This loose fitting arrangement results in the center conductor of the cable not being well supported whereupon the center conductor can be bent as the guide is maneuvered through the post.  
         [0026]     As illustrated in  FIGS. 2-4 , in one embodiment of the invention, the guide  30  is an elongated triangular-shaped member that has sides  31 - 33  that come together to form three corners  34   a ,  34   b ,  34   c . A slot, generally referenced  35 , extends axially along the length of the guide body. The guide includes a slit that passes inwardly through one of the side walls  31  of the guide and passes into the slot through entrance  40 . The slit  38  provides a side access passage for the center conductor of the coaxial cable to slot  35 . The throat width of the entrance is slightly less than the diameter of the center conductor  20  of the coaxial cable, the reason for which will be made clear from the disclosure below.  
         [0027]     Preferably, the guide is extruded from a resilient material such as plastic, rubber, or any suitable elastomeric material or the like. Sufficient resilience is provided to the guide body so that the center conductor of the cable can be passed radially through the slit  38  as illustrated in  FIG. 3  and snap fitted into the slot through the entrance throat  40 . The slot in this embodiment is circular and has a diameter wherein the center connector of the cable is in a tight frictional fit in the slot once the center connector has been snap fitted into the slot. The slot of the guide may take a variety of shapes such as square, rectangular, oval, or trapezoidal, so long as the center conductor is supported snuggly within the passage once the center conductor is snap fitted in place through the entrance of the slit  38 .  
         [0028]     Turning now to  FIG. 4 , the triangular-shaped guide  30  has three contact surfaces or points  34   a ,  34   b ,  34   c  that are arranged to ride in sliding contact against the inner wall surface  43  of the post  15  of the end connector. To gain entry into the post, the resilient guide is compressed to close the slit prior to insertion into the post. Once inserted, the compressing force is released and the corners of the guide move back into biasing contact against the inside wall surface of the post. This three point contact is sufficient to hold the guide centered in the post while minimizing the amount of friction that can be generated between the mating parts. Accordingly, the guide can be easily passed in sliding contact through the post.  
         [0029]     In practice, the cable is brought to a desired position inside the post and the cable is then restrained from further movement while the guide is passed completely through the post clear of the end connector.  
         [0030]      FIG. 5  illustrates a further embodiment of the invention wherein the body of the guide  45  is again triangular-shaped. The slit  46  diverges from a wide opening at side wall  48  to entrance  49  of the central slot  50 .  
         [0031]      FIG. 6  illustrates a guide  55  that has a substantially square cross-section. The guide further contains a slot  56  that is aligned along the center axis of the guide. A longitudinal slit  57  passes from the exterior surface  58  of the guide and opens into the central slot  56  through entrance  59 . Here again, the center conductor of the coaxial cable  20  can be snap fitted into the central passage through the slit  57 . In this embodiment of the invention, the guide has four corners that are arranged to ride in sliding contact with the interior surface of the connector post.  
         [0032]     The elongated guide  60  as shown in  FIG. 7  contains a trapezoidal-shaped center slot  61 . A diverging slit  64  beginning at the exterior surface of the guide passes into the central passage through an entrance  65 .  
         [0033]     The embodiment illustrated in  FIG. 8  slot has a body  71 , which contains a triangular-shaped central slot  72 . A diverging slit  73  which is centered upon the apex of the triangle begins at the exterior surface  74  of the guide and opens into the slot through an entrance  75 .  
         [0034]      FIG. 9  further illustrates a guide  80  having a square-shaped central slot  81 . A diverging slit  82  passes downwardly from the exterior surface  83  and opens into the central slot  71  through an entrance  85 .  
         [0035]     The guide  90  that is illustrated in  FIG. 10  has an oval-shaped central slot  81  that is axially aligned along the central axis  92  of the guide. A slit  94  extends downward from the exterior surface  95  of the guide and opens into the central slot through an entrance  96 . The remaining walls of the guide each contain V-shaped groove  97  that extends inwardly from the outer surface of each wall to a given depth. The V-shaped grooves in the walls of the guide provide weakened sections to the guide that serve to permit the guide to be easily compressed in a number of different directions as it passes through the post of the end connector.  
         [0036]      FIGS. 11 and 12  show the manner in which the guide shown in  FIG. 10  is used with the prepared end of a coaxial cable  10 . The guide  90  is inserted into post  15 . The center conductor  20  of cable in one form can be brought into contact with slit  94  and easily moved through the slit to engage the central slot  91 . Once engaged as depicted in  FIG. 12 , the cable can be advanced into the connector with the center conductor being properly guided and aligned so that the post engages the cable between the dielectric layer  26  and the wire mesh  28 .  
         [0037]     While this invention has been particularly shown and described with reference to the preferred embodiment in the drawings, it will be understood by one skilled in the art that various changes in its details may be effected therein without departing from the teachings of the invention.