Patent Publication Number: US-6712647-B2

Title: Terminated coaxial connector

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This is a Continuation-in-Part of U.S. patent application Ser. No. 10/201,621 filed Jul. 22, 2002 now ABN. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to connectors for terminating coaxial telecommunications ports. 
     BACKGROUND OF THE INVENTION 
     In telecommunications installations, coaxial jacks are used to connect equipment at different locations within a telecommunications wiring closet or to other devices in the telecommunications system. It is not uncommon for jacks to be wired to one piece of equipment and not have a plug inserted in the jack to connect to a second piece of equipment. In these situations, it is desirable to insert a terminated plug in the jack to close the circuit and provide an appropriate level of impedance in the circuit as opposed to leaving the circuit open. The terminated plug will preferably provide a fixed and known amount of impedance matched to the particular requirements of the installation. 
     Known terminated plugs provide an outer shell and a center conductor connected directly by a resistor within and soldered to the outer shell. Known terminated plugs may not provide an stable or desirable level of impedance due to the resistor being angled within the outer shell, improperly contacting the outer shell or the solder connection between the outer shell and resistor being improper or inconsistent. Improvements to known terminated coaxial plugs are desirable. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a terminated coaxial connector including a resistor to provide a desired level of impedance. The resistor is held within an conductive outer housing and electrically links a center conductor and the outer housing via an conductive end plug. The end plug is crimped about an end of the resistor and maintains the resistor in axial alignment within the outer housing. The present invention further relates to a method of assembling a terminated coaxial connector including a resistor wherein an end of the resistor is inserted within and crimped to a rear plug which holds the resistor axially aligned within a hollow core of a conductivew outer housing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate several aspects of the present invention, and together with the description, serve to illustrate the principles of the invention. A brief description of the drawings is as follows: 
     FIG. 1 is a front perspective view of a prior art terminated coaxial connector. 
     FIG. 2 is an exploded front perspective view of the prior art terminated coaxial connector of FIG.  1 . 
     FIG. 3 is a cross-sectional view of the prior art terminated coaxial connector of FIG.  1 . 
     FIG. 4 is a front perspective view of a terminated coaxial connector in accordance with the present invention. 
     FIG. 5 is a side view of the terminated coaxial connector of FIG.  4 . 
     FIG. 6 is an exploded front perspective view of the terminated coaxial connector of FIG. 4 . 
     FIG. 7 is a cross-sectional view of the terminated coaxial connector of FIG. 4 taken along line  7 — 7  in FIG.  5 . 
     FIG. 8 is a rear perspective view of a rear plug for use with the terminated coaxial connector of FIG.  4 . 
     FIG. 9 is a front view of the rear plug of FIG.  8 . 
     FIG. 10 is a cross-sectional view of the rear plug of FIG. 8, taken along line  10 — 10  in FIG. 9 . 
     FIG. 11 is a front perspective view of an end cap for use with the terminated coaxial connector of FIG.  4 . 
     FIG. 12 is a front end view of the end cap of FIG.  1 . 
     FIG. 13 is a cross-sectional view of the end cap of FIG. 11 taken along line  13 — 13  in FIG.  12 . 
     FIG. 14 is a front perspective view of a first alternative terminated coaxial connector in accordance with the present invention. 
     FIG. 15 is an exploded front perspective view of the terminated coaxial connector of FIG.  14 . 
     FIG. 16 is a side view of the terminated coaxial connector of FIG.  14 . 
     FIG. 17 is a cross-sectional view of the terminated coaxial connector of FIG. 14, taken along line  17 — 17  of FIG.  16 . 
     FIG. 18 is a front perspective view of a second alternative terminated coaxial connector is accordance with the present invention. 
     FIG. 19 is a rear perspective view of the terminated coaxial connector of FIG.  18 . 
     FIG. 20 is an exploded front perspective view of the terminate coaxial connector of FIG.  18 . 
     FIG. 21 is a side view of the terminated coaxial connector of FIG.  18 . 
     FIG. 22 is a cross-sectional view of the terminated coaxial connector of FIG. 18 taken along line  22 — 22  in FIG.  21 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference will now be made in detail to the exemplary aspects of the present invention that are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or similar parts. 
     When terminating unused ports in a coaxial telecommunications installation, it is desirable to have terminated coaxial connectors with specific levels of impedance. For a BNC terminated coaxial plug connector, the desired level of impedance across the connector is 75 Ohms. For other types and styles of coaxial connectors, other levels of impedance may be preferred. 
     A prior art terminated coaxial plug connector  110  is shown in FIGS. 1 through 3 and includes a mating opening  112  for mating with a coaxial jack. A rotating locking mechanism  118  engages the coaxial jack to prevent inadvertent or accidental removal. Within a cylindrical conductive outer shell  114  is mounted an insulator  122  which electrical isolates a center conductor  116  substantially in the center of mating opening  112 . A first lead or end  126  of a resistor  124  is mounted to center conductor  116  opposite mating opening  112  and electrically connects conductive outer shell  114  and center conductor  116  at a second lead or end  128 . A rear cap  120  encloses the rear of terminated coaxial connector  110 . 
     In use, connector  110  is attached to a coaxial connector jack. Outer shell  114  contacts a ring conductor of the jack and center conductor  116  contacts a tip conductor of the jack. Resistor  124  electrically connects outer shell  114  and center conductor  116  to provide a return signal on the circuit connected to the jack. The level of impedance of this return signal is governed by resistor  124 . 
     While resistor  124  may be inserted substantially axially aligned within outer shell  114 , when second end  128  is connected to outer shell  114 , resistor  124  becomes displaced from this axial alignment, often to such an extent that resistor  124  comes into contact with outer shell  114 , as shown in FIG.  3 . The connection between second end  128  and outer shell  114  is typically a physical and electrical connection such as a solder connection. Second end  128  may extend outside of outer shell  114  through a notch  132  and be received within a relief  130  in outer shell  114 . In such a connection, rear cap  120  would serve to provide additional security to the physical and electrical connection between second end  128  and outer shell  114 . It is very difficult to assemble a terminated connector such as coaxial connector  110  without displacing resistor  124  in the process of bending second end  128  and soldering second end  128  to outer shell  114  from the desired axial alignment shown. When such displacement occurs, the impedance provided by connector  110  will vary from the desired impedance. Resistor  124  may come into contact with outer shell  110 , the solder joint between second end  128  and outer shell  114  may vary in the quality of electrical connection provided, placement of rear cap  120  about the completed solder joint may change the nature of the physical and electrical connection provided by the solder joint, all of which may cause unpredictable and undesirable changes in the level of impedance provided by connector  110 . 
     FIGS. 4 through 7 show a terminated coaxial connector  10  in accordance with the present invention. Connector  10  including an axially aligned resistor  24 . Connector  10  is a BNC style connector and defines a mating opening  12 . Connector  10  further includes a cylindrical conductive outer housing  14 , a center conductor  16  within mating opening  12  and a locking mechanism  18  about outer housing  14 . An insulator  22  is mounted within outer housing  14  and provides a center axial channel  32  into which a center conductor  16  is mounted with a first end  36  extending into mating opening  12 . Insulator  22  holds center conductor  16  axially aligned within outer housing  14  and electrically isolates center conductor  16  from outer shell  14 . A first end  26  of resistor  24  is crimped onto a second end  34  of center conductor  16 . A second end  28  of resistor  24  is inserted through and crimped to a rear plug  30 . Rear plug  30  is mounted to an end of outer housing  14  opposite mating end  12  and is electrically conductive to provide an electrical path between resistor  24  and outer housing  14 . A rear cap  20  in mounted over rear plug  30 . 
     The crimped connection between second end  28  and rear plug  30 , and the physical connection between outer housing  14  and rear plug  30  when rear plug  30  is mounted as shown in FIGS. 4 to  7  provide a consistent electrical connection between resistor  24  and outer housing  14 . The crimping and physical connections do not require heating or soldering. Rear plug  30  supports resistor  24  so that resistor  24  remains in a consistent axially aligned position within outer housing  14 . The quality of the connections and the consistent location of resistor  24  within connector  10  allow connector  10  to provide a predictable level of impedance when connector  10  is used to terminate an open circuit through a coaxial connector jack. 
     Also shown in FIGS. 4 through 7 are washers  38  and  42  and a wave washer  40 , which cooperate to aid in the rotation and lateral movement of locking mechanism  18  about outer housing  14 . 
     Referring now to FIGS. 8 through 10, additional details of rear plug  30  are shown. Rear plug  30  is made of an electrically conductive material and includes a central axial opening  44  through which is received second end  28  of resistor  24 . A bevel  48  aids in the insertion of second end  28  into opening  44 . Opposite bevel  48  is a crimp extension  46  which is compressed about second end  28  to crimp rear plug  30  to resistor  24 . Rear plug  30  also includes a first wall  50  which is inserted within outer housing  14 . First wall  50  may be knurled as shown to aid in insertion and improve the physical and electrical connection between rear plug  30  and outer housing  14 . A lip  54  engages an end of outer housing  14  opposite mating end  12  and serves as a depth limiter for the insertion of rear plug  30  within outer housing  14 . A second wall  52  has a greater diameter than first wall  50 . Second wall  52  has a diameter approximately the same as a rear portion  68  of outer housing  14  and engages an interior wall  64  of rear cap  20 , discussed in further detail below. Second wall  52  may also be knurled as shown to aid the insertion of rear cap  20  about rear plug  30  and rear portion  68  and improve the physical connection of rear cap  20  and rear plug  30 . 
     FIGS. 11 through 13 show rear cap  20  including a cylindrical interior space  56  closed at one end by an end wall  66 . Cylindrical interior  56  includes a first portion  58  enclosed by a wall  62  and a second portion  60  enclosed by wall  64 . First portion  58  has a larger diameter than rear portion  68  and second wall  52 . When positioned about outer housing  14  and rear plug  30  as shown in the earlier FIGS., inner wall  64 , which has a marginally smaller diameter than second wall  52 , engages rear plug  30  and is held to connector  10 . It is contemplated that other combinations of inner diameters within rear cap  20  and outer diameters of outer housing  14  and rear plug  30  may be used to secure rear cap  20  about rear portion  68  of connector  10 . 
     Referring now to FIGS. 14 through 17, a first alternative embodiment terminated coaxial connector  210  is shown, for use with WECO mid-size telecommunications jacks. The structure of connector  210  is substantially similar to that of connector  10 , with several components having slightly different shapes to mate with the tip and ring contacts of the mid-size jack. A pair of insulator halves  222  centrally mount a center conductor  216  within an outer housing  214  so that a first end  236  is within a mating end  212 . First end  26  of resistor  24  is crimped to a second end  234  of center conductor  216  and second end  28  is crimped within an opening  244  of a rear plug  230 . Rear plug  230  is mounted within a rear portion  268  of outer housing  214  and a rear cap  220  is mounted about rear portion  268  so that a first interior wall  264  of rear cap  220  engages a second wall  252  of rear plug  230  and a second interior wall  262  of rear  230  engages a raised area  270  to secure rear cap  220  to connector  210 . 
     Referring now to FIGS. 18 through 22, a second alternative embodiment terminated coaxial connector  310  is shown, for use with F-connector telecommunications jacks. The structure of connector  310  is substantially similar to that of connector  10 , with several components having slightly different shapes to mate with the tip and ring contacts of the F-connector jack. A pair of insulator halves  322  centrally mount a center conductor  316  within an outer housing  314  so that a first end  336  is within a mating end  312 . First end  26  of resistor  24  is crimped to a second end  334  of center conductor  316  and second end  28  is crimped at a crimp sleeve  346  within an opening  344  of a rear plug  330 . Rear plug  330  is mounted within a rear portion  368  of outer housing  314  so that first wall  350  engages an interior wall  351  of outer housing  314 . No rear cap is shown mounted to connector  314  although a rear cap could be adapted to fit about rear portion  368  similar to the previously disclosed embodiments. 
     Additional embodiments of terminated coaxial connectors in accordance with the present invention may be adapted for other standard or proprietary coaxial connector jacks. These other jacks include but are not limited to TNC, RCA, WECO standard size, MUSA mini and standard size, 7-16 DIN, N-format, 1.6/5.6 and LCJ jacks. The adaptations required to construct terminated coaxial connectors in accordance with the present invention will be similar to the adaptations made for the two alternative embodiments described above, wherein the mating end portion of the connector will be adapted to fit the jack, while the rear portion of the plug will include the outer housing or ring conductor, the resistor crimped to the center or tip conductor and a rear plug holding the resistor fixed axially within the housing. 
     A method of assembly of connector  10  may include inserting and press-fitting insulator  22  within outer housing  14 , where friction will hold insulator  22  in place. First end  26  of resistor  24  is trimmed to a desired length, for example, in the illustrated embodiment of connector  10 , first end  26  preferably extends approximately 0.20 inches from resistor  24 . First end  26  is inserted within an opening in second end  34  of center conductor  16 . Second end  34  of center conductor  16  is crimped about first end  26 , securing and electrically connecting resistor  24  and center conductor  16 . Second end  28  of resistor  24  is then placed within opening  44  of rear plug  30 . The combination of center conductor  16 , resistor  24  and rear plug  30  are then connected with outer housing  14  by inserting and press-fitting center conductor  16  within axial opening  32  of insulator  22  and inserting and press-fitting rear plug  30  into rear portion  68  of outer housing  14 . 
     So assembled, resistor  24  is axially aligned within outer housing  14  and electrically connected to outer housing  14  by electrically conductive rear plug  30 . Tension is then applied to second end  28  of resistor  24  to ensure that resistor  24  is not canted within outer housing  14 . Crimp sleeve  46  of rear plug  30  is then compressed and crimped about second end  28  of resistor  24 . Second end  28  is then trimmed substantially flush with crimp sleeve  46 . So crimped at both ends, resistor  24  is now held axially aligned within outer housing  14  so that a consistent level of impedance can be provided by connector  10 . Rear cap  20  is placed over rear portion  68  of connector  10  and secured in place. Rear cap  20  provides additional protection to the internal components of connector  10 . Alternative assembly approaches are anticipated and suggested by the foregoing description within the scope of the present invention. 
     The above specification, examples and data provide a complete description of the manufacture and use of the composition of the invention. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended.