Abstract:
The invention is directed to a crimp plug having a front portion, a center portion, and a securing portion. A conductor receiving cavity extends from the front e into the center portion. A stop shoulder within the center portion provides transition from the conductor receiving cavity to a plurality of conductor receiving passageway extending to a rear end. Each conductor receiving passageway serves to properly position the conductors while the stop shoulder serves to control the insertion length. A securing portion extends from the center portion and provides for securing of the cable.

Description:
BACKGROUND 
     The invention is related to fiber optic or electrical connectors. More particularly, the invention is related to a crimp plug for use in such connectors. 
     Connectors typically are utilized for terminating a plurality of conductors. These conductors may be either electrical wires or fiber optic light guides such as fibers. The conductors are typically arranged in a cable having an outer jacket surrounding a plurality of insulated conductors. In between the conductors and the outer jacket, other optional components of the cable include shielding, strength members, or intermediate insulated layers. In order to terminate the conductors, the outer jacket and the other optional components are typically stripped back from the individually insulated conductors. Individually insulated conductors may be utilized without an outer jacket. Each of the insulated conductors is then further stripped to expose and terminate the respective conductor to the connector. The conductors are typically inserted from a rear end of the connector. Various terminations may be utilized. For example, in electrical connectors, each wire is typically terminated to either a pin or a socket and then inserted into the connector housing. For fiber optic connectors, each individual fiber or a plurality of fibers is typically terminated to a l-rule which is then inserted into the connector housing. 
     The conductors are often passed through intermediate components before entering the conductor receiving end of the housing. These intermediate components may be utilized to properly position a plurality of conductors for terminations at a mating end of the housing. One such intermediate component is known as a crimp plug. Typically, a crimp plug is positioned at the rear end of the connector housing and receives the plurality of conductors through a cavity passing from the rear end into the connector housing. An outer surface of the crimp plug receives the outer jacket of the cable and a crimp ring is compressed over the outer jacket to secure the outer jacket to the crimp plug. In the case where individually insulated conductors are used the crimp ring is not used. The stripped conductors pass through the crimp plug for termination at the mating end of the connector housing and the crimp plug is typically secured within the rear end of the connector housing. 
     U.S. Pat. No. 5,367,595 (Jennings et al.) discloses a fiber optic connector for joining a bundle of jacketed optical fibers to an optical device that requires a linear array or arrays of stripped optic fibers at the connection interface. Block shaped portions are provided in the connector for receiving jacketed fibers. The grooves have a transition portion so that a front portion is large enough to accommodate only stripped cores of the fibers. Complementary posts and holes are utilized for assembling block portions to each other. An inner wedge member is attached to an outer cell which encases the assembled block portions. Resilient latch fingers are provided on the back wall of the shell for retaining fibers which have been prepared as shown in FIG. 4 of that patent. Alternate embodiments are also shown wherein slots have transition sections each for receiving a jacketed fiber or a stripped core. 
     U.S. Pat. No. 5,915,055 (Bennett et al.) shows a method and apparatus for connectorizing fiber optic cable. The apparatus has a jumper buffer seat and a jumper insert. The jumper buffer seat features bores having tapered openings to facilitate insertion of stripped and of jumpers or fibers through the bores. a Small flats are provided along the tapered sections for allowing only stripped fibers to pass into the forward sections, of the bore. The jumper insert has a singular tapered channel for transitioning the plurality of fibers into a linear array. A completed splice is enclosed in the splice housing. 
     U.S. Pat. No. 4,368,948 (Despouys) teaches a fiber optic connector ferrule having a support sleeve preferably made of a deformable metal material. The support sleeve is inserted into a barrel having a passage which is large enough to only pass a stripped fiber. The fiber is fixed to the ferrut by crimping the sleeve. 
     While these patents show devices for limiting conductor insertion, none provide a method for terminating or securing an outer jacket. Known crimp plugs, while providing a method for securing an outer jacket, do not provide control of conductor insertion length. A problem therefore exists with such crimp plugs in that during assembly, the pre-stripped cable is manually inserted into the rear end of the crimp plug until a desired length of stripped conductors extend out of the front end. When handling a plurality of conductors, it is often difficult to achieve equal lengths of stripped conductors extending out of the front end. If some conductors are inserted farther than others, additional stresses will be applied to these conductors when a pulling force is applied to the terminated cable in a completed connector assembly. 
     An additional problem exists in that crimp plugs having a singular cavity for receiving a plurality of conductors present difficulty in properly arranging the conductors for termination at the mating end of the connector. Once the singular cavity is populated with conductors, the conductors must be manually arranged to be terminated in their respective positions at the mating end of the connector. 
     SUMMARY 
     It is therefore an object of the invention to provide an improved crimp plug for use in a connector wherein insertion length and positioning of the conductors are controlled. 
     This and other objects have been achieved by providing a crimp plug having a front portion which is insertable into the cable receiving end of a connector, a mid portion having a passageway for receiving a plurality of conductors, and a securing portion extending rearward from the mid portion. The securing portion has a plurality of conductor receiving passageways extending from a rear end into the mid portion. A stop shoulder is provided within the crimp plug to control conductor insertion length. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will now be described by way of example with reference to the accompanying figures of which: 
     FIG. 1 is a three-dimensional front view of the crimp plug according to the present invention. 
     FIG. 2 is a three-dimensional rear view of the crimp plug in FIG.  1 . 
     FIG. 3 is a three-dimensional rear view showing the crimp plug FIG. 2 assembled into a connector. 
     FIG. 4 is a cross-sectional view of the assembled crimp plug and connector taken along the line  4 — 4  of FIG.  3 . 
     FIG. 5 is a cross-sectional view of the crimp plug taken along the line  5 — 5  of FIG.  1 . 
     FIG. 6 is a cross-sectional view of the crimp plug taken along the line  6 — 6  of FIG.  5 . 
     FIG. 7 is a cross-sectional view of the crimp plug taken along the line  7 — 7  of FIG.  5 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The crimp plug  10  of the present invention will first be described generally with reference to FIG.  1 . The crimp plug has three major portions. A front portion  20  extends from a center portion  40  and securing portion  60  extends rearward from the center portion  40  opposite the front portion  20 . A plurality of conductor receiving passageways  64  extend from a rear end  62  toward the center portion  40 . These conductor receiving passageways  64  are in communication with semicircular passageways  24  passing through the front portion  20  to a front end  22 . Securing projections  26  are provided along sides of the front portion  20  and ridges  66  are provided along the outer surface of the securing portion  60  and extend transverse to the conductor receiving passage ways  64 . 
     Each of the major portions  20 ,  40 ,  60  will now be described in greater detail. The front portion  20  is generally how as best shown in FIGS. 1 and 5. Semicircular passageways  24  extend from the front end  22  through a conductor receiving cavity  25 . A pair of securing projections  26  extend from outer surfaces of opposing side walls. 
     The center portion  40  is also generally hollow and has an outer dimension which is larger than the outer dimensions of the front portion  20 . A front transition  42  is disposed between the front and center portions  20 ,  40 . Similarly, a rear transition  44  is disposed between the center portion  40  and the securing portion  60 . The conductor receiving cavity  25  extends from the front end  22  through the front portion  20 , and into the center portion  40 . Each semicircular passageway  24  ends at a stop shoulder  28  disposed within the center portion  40 . Likewise, the conductor receiving cavity  25  ends at the stop shoulder  28 . A plurality of conductor receiving passageways  64  extends from the stop shoulder  28  to the rear end  62 . Each conductor receiving passageway  64  is generally circular and dimension to receive an insulated conductor. It should be understood by those reasonably skilled in the art that the conductor receiving passageways  64  should be shaped and dimensioned to receive a desired conductor  74 . In this embodiment, the conductors are shown as optical fibers  78  having generally circular cross sections surrounded by circular insulators known as buffers. It should also be understood that the conductors  74  may be electrical, may have several layers surrounding each conductor, and may have different cross sections. 
     The securing portion  60  begins at the rear transition  44  and extends to the rear end  62 . The securing portion  60  is dimensioned to be slightly smaller than the center portion  40 . The rear transition  44  is disposed between the center portion  40  and the securing portion  60 . The securing portion  60  is generally oval in cross-section, however, it may take other shapes as appropriate to secure the desired cable  70  as will be described below. Along the outer surface, a plurality of ridges  66  extend in a direction transverse to the conductor receiving passageways  64 . Each conductor receiving passageway  64  extends from within the center portion  40  through the securing portion  60 . It should be understood by those reasonably skilled in the art that while the stop shoulder  28  is shown within the center portion  40  at a desired location, this stop shoulder  28  and transition between the conductor receiving passageways  64  and the semicircular passageways  24  may be moved along the conductor receiving cavity  25  as desired. 
     Installation of a cable  70  into the crimp plug  10  will now be described in greater detail with reference to FIGS.  3 , 5 , 6  and  7 . The cable  70  is first stripped to remove a portion of the outer jacket  70  thus exposing a length of conductors  74 . Each conductor is further stripped to remove a portion of a buffer  75  and then inserted into respective conductor receiving passageway  64  from the rear end  62  as best shown in FIG.  3 . The conductors  74  are finally positioned within respective conductor receiving passageways  64  so that each buffer  75  abuts stop shoulder  28  as shown in FIGS. 5 and 7. The individual conductors  78  or fibers pass through the conductor receiving cavity  25 , and out of the front end  22 . The outer jacket  72  is disposed over the securing portion  60 . It should be noted that in FIG. 5, intermediate layers  79  are also placed over the securing portion  60  underneath the outer jacket  72 . In the case of a fiber optic cable, these may be strength members. The crimp ring  68  is then positioned over the outer jacket  72  and compressed or crimped over securing portion  60  as best shown in FIG.  6 . Upon compression, the outer jacket  72  is prevented from moving rearward by the interaction of the crimp ring  68  and ridges  66  of the securing portion  60 . The boot  76  is then slid over the crimp ring  68 . It should be understood by those reasonably skilled in the art that single conductors can also be assembled to the crimp plug  68 . Each of the single conductors could be assembled just as the conductors  74  of the cable  70  are assembled. In the case of single conductor assemblies however, a crimp ring  68  is not required. Instead, the boot  76  is applied directly to the securing portion  60  and held there by a frictional fit with the ridges  66 . 
     Assembly of the cable  70  and crimp plug  10  to a connector  80  will be described with reference to FIG.  4 . In this embodiment, the connector  80  is an optical connector, however it should be understood that it may be substituted by an electrical connector having electrical conductors instead of optical fibers. The crimp plug  10  is insertable into the connector  80  from a cable receiving end  82 . The front portion is positioned within the connector  80  and is secured into the connector  80  by securing projections  26  which reside in openings  88 . The crimp plug  10  also serves to compress the biasing spring  84  and urge a ferrule  86  toward a mating end  89 . The fibers  78  have been previously terminated to the ferrule  86  by known techniques. 
     An advantage of the invention is that conductors  78  of the cable  70  may be assembled into the crimp plug  10  to exit the front end  22  having the desired length controlled by the stop shoulder  28 , and having the desired position controlled by the conductor receiving passageways  64 . An additional advantage is that positioning and length are controlled within a single assembly which also provides securing through the securing portion  40 .