Patent Publication Number: US-2004057672-A1

Title: Process for field terminating an optical fiber connector

Description:
BACKGROUND OF THE INVENTION  
       [0001] 1. Field of the Invention  
       [0002] The invention relates to devices for preparing and terminating optical fibers for interconnection in telecommunications networks using plug and socket assemblies that align the optical fibers for optimal signal transmission without the use of ferrules. More particularly, the present invention facilitates field processing of one or more cleaved and polished bare fiber ends using an apparatus for temporary containment during suitable preparation of terminal portions of optical fiber cables for field installation into the plug portion of an optical fiber plug and receptacle connector.  
       [0003] 2. Description of the Related Art  
       [0004] The use of optical fibers in telecommunications networks offers the advantage of broader bandwidth when compared to the copper wire systems that have dominated this industry. Today&#39;s high speed, bandwidth-intensive computing environments provide justification for increased use of optical fiber cables. The demand for optical fiber is expected to increase as transmission protocols reach higher and higher speeds and bandwidth requirements continue to grow. Until recently, cost was a deterrent to the use of optical fiber systems. The impact of cost has become less severe because of improvement in the supporting electronics and optical communications infrastructure. In addition, an increase in the volume of optical fiber production has driven down the cost of optical fiber components and devices. Optical fiber systems will become the preferred choice as component and installation costs approach parity with copper wire systems.  
       [0005] As with copper wire, it is necessary to provide means for interconnection and termination of optical fibers. Interconnection of optical fibers may be achieved by a number of methods including the methods of splicing and connecting. A splice is generally understood to be the formation of a permanent connection between a pair of optical fibers. The act of connecting optical fibers requires a device, i.e. a connector that facilitates repeated engagement and disengagement of optical fibers. An optical fiber connector, for one or more optical fibers, typically includes a plug portion and a receptacle or socket portion. Insertion of the plug portion into the receptacle portion provides interconnection for optical signal transmission between optical fibers. During the mating of a plug portion with a receptacle portion of an optical fiber connector, there is the need to provide accurate axial alignment of lengths of optical fiber for the number of optical fibers contained within each plug or receptacle. One requirement of an optical fiber connector is the joining together of lengths of optical fibers so aligned that light energy will propagate from one fiber to the other without insertion loss that may be observed as an appreciable light attenuation. To reduce insertion loss at the point of optical fiber connection, it is necessary to have precise registration and abutting fiber contact across the entire end of each optical fiber end face.  
       [0006] A broad range of devices exist for connecting and aligning optical fibers, whether the connection includes only a pair of optical fibers, i.e. one optical fiber in both the plug and receptacle portion of the optical fiber connector, or two or more fiber pairs. The majority of connectors include ferrules that rely on alignment of the outer surface of each ferrule to provide fiber alignment during termination, polishing and a positioning of each optical fiber end in an optical fiber connector.  
       [0007] A relatively recent development in optical fiber interconnection devices eliminates the need for ferrule-terminated optical fibers. These alternate plug and socket connectors use fiber guiding V-grooves to align cleaved and polished end portions of stripped optical fibers for optimum signal transmission. Connector assemblies using V-grooves for optical fiber alignment are adaptable to the needs of simplex (one fiber), duplex (two fibers), and multiplex (two or more fibers) connectors. They also offer advantages over ferrule-terminated optical fibers such as fewer component parts, smaller size and convenient assembly.  
       [0008] Further discussion emphasizes connector assemblies using V-groove alignment of optical fibers that undergo repeated engagement and disengagement. U.S. Pat. No. 5,381,498 describes a modular, multi-fiber connector comprising a plug and receptacle having an appearance similar to a conventional RJ 45 jack for copper conductors. The plug includes a body having a surface with several grooves that position and limit movement of otherwise free end portions of optical fibers. Fibers inside the receptacle are free to move into the grooves inside the plug body and into forcible abutment with the terminal ends of the plug fibers during insertion of the plug through an opening in the body of the receptacle. U.S. Pat. Nos. 5,757,997 and 6,026,210 and related patents, for example, describe subsequent development of connectors using V-groove alignment of optical fibers. These later versions of optical fiber connectors include features such as internal fiber splices using crimp elements, similar to those described in U.S. Pat. No. 5,638,477, and optical fiber holders of the type described in U.S. Pat. No. 6,078,719. Optical fiber holders become permanently applied around one or more optical fibers during fiber preparation using a device that cleaves stripped terminal portions of one or more optical fibers to a length determined by the dimensions of the optical fiber receptacle. The cleaving process has the capability for precise cleaving and polishing to produce multiple optical fibers having substantially the same length. U.S. Pat. Nos. 5,813,902, and 6,099,392 further describe systems and processes for cleaving and polishing terminal portions of optical fibers prior to assembly of connector receptacles or sockets in the field.  
       [0009] Implementation of optical fiber cable networks using cable interconnection based upon V-groove connectors requires field termination for either a connector receptacle or a connector plug or both. Field installation of optical fiber cables employs known methods for applying a receptacle or socket to a stripped end portion of one or more optical fibers. The lack of a corresponding method for field installation of connector plugs limits field-termination capability to optical fiber cables having a connector receptacle at each end. This limitation restricts optical fiber cable interconnection to a single option in which field-terminated cables, having connector receptacles at both ends, alternate with factory terminated cables, having connector plugs on both ends. Factory production of connector plug terminated optical fiber cables typically provides a limited variety of standard cable lengths. The use of pre-terminated standard lengths of optical fiber cable prevents the use of normal methods for installing optical fiber cable by pulling it through cable ducts or the like before applying connector plugs and sockets for interconnecting lengths of cable. Pre-terminated, factory assembled, optical fiber cables add expense and require more cable duct space than conventional cable systems. Reliance on standard lengths of terminated cables also denies the advantage of efficient use of space associated with custom installations. To provide more options and to facilitate installation of custom cable networks, there is a need for field installable optical fiber connector plugs so that cable network installers may choose whether to terminate a particular cable with either a connector plug or a connector socket.  
       SUMMARY OF THE INVENTION  
       [0010] The present invention provides an apparatus used during cleaving and polishing of optical fibers to be inserted into a connector plug body that accommodates one or more optical fibers. Connector plugs according to the present invention include several different embodiments having design features that facilitate preparation and insertion and splicing of optical fibers by a person who is relatively unskilled as an assembler of optical fiber connector components. Optical fiber insertion may be done by hand as a field operation requiring only the use of a crimp tool, for crimp element closure, to secure and retain one or more spliced optical fibers inside a connector plug.  
       [0011] Field installation of optical fiber connector plugs, in conjunction with the previously discussed field installable receptacles, offers several benefits including convenience, development of custom network segments, and the opportunity to order bulk supplies, rather than an array of standard components. These benefits could contribute to a reduction of optical fiber cable network installation costs.  
       [0012] The use of connector plugs and processes according to the present invention with previously available field installable sockets is convenient because it moves optical fiber termination from the controlled assembly environment of the factory to the field location where actual installation requirements are more clearly seen. Given the opportunity to construct cable systems to match the needs of a particular installation, an assembler is no longer limited to using factory terminated, standard cable lengths but has the advantage of custom building interconnecting cables. Custom interconnecting cables may be prepared using bulk optical fiber cable and connector components that may prove to be a less expensive option than reliance on supplier-determined, standard lengths of plug terminated cables. Field termination of connector plugs allows cable installers to return to more conventional methods of network installation.  
       [0013] The present invention includes an article used in the process of cleaving and polishing the ends of optical fibers before termination inside a connector plug or socket of an optical fiber connector assembly. An optical fiber connector assembly includes a connector plug and socket having V-grooves, rather than ferrules, for aligning cleaved and polished ends of terminal portions of optical signal-carrying optical fibers.  
       [0014] Articles for preparing optical fibers for termination are referred to herein as “pucks” for cleaving and polishing optical fiber ends. Initial preparation of a cable, containing one or more individual optical fibers, requires that the sheath and buffer layers be stripped from a generous terminal portion of each optical fiber.  
       [0015] A puck, as described herein, has a design with enough room to accommodate a single optical fiber or multiple fibers simultaneously during the process of optical fiber cleaving and polishing. Simultaneous processing of multiple fibers produces cleaved and polished optical fiber ends on stripped terminal fiber portions of equal and precisely controlled length. The length requirements match those needed for optimum fiber positioning after insertion into the body of any of the embodiments of optical fiber connector plugs according to the present invention.  
       [0016] The process of cleaving and polishing the ends of optical fibers includes temporary insertion of stripped optical fiber terminal portions into a fiber holder that includes a spring clamp. Preparation for cleaving of optical fiber ends requires placement of the fiber holder in a recess in the puck so that short lengths of one or more optical fibers extend from the holder to pass through openings in a guide plate opposite a holder entry port that receives a portion of un-stripped optical fiber cable. Correct positioning of the holder in the recess places the jacketed cable, exiting the holder entry port, in a groove in the puck. A hinged lid, attached to the puck, closes over the holder and the jacketed optical fiber cable to grip the cable and actuate the spring clamp in the holder. A latching mechanism secures the hinged lid to the body of the puck preventing movement of either the un-stripped, jacketed cable or the stripped optical fiber terminal portions during cleaving of optical fiber ends. After loading and securing the holder and the optical fiber cable in the puck, cleaving of immobilized optical fibers produces optical fiber terminal portions of precise and equal length based upon the design and dimensions of the puck. The guide plate has a shape for mating in a required, fixed orientation with a groove in a cleaving and polishing device. After correct positioning of the puck, using the guide plate, stripped optical fibers, extending from the guide plate, are essentially perpendicular to a cleaving blade of the cleaving and polishing device. Smooth movement of the puck past the cleaving blade produces one or more cleaved optical fibers that optionally have slightly angled end faces at an angle of 10° or less. Slightly angled and polished optical fiber end faces have been shown to provide optical splices that transmit optical signals with less signal attenuation than optical splices in which the polished end faces are substantially perpendicular to the longitudinal axis of the optical fiber.  
       [0017] The puck may be removed from the cleaving section of the cleaving and polishing device and, while still in the puck, and with the lid in its latched position, the cleaved optical fiber ends may be polished against a polishing strip using several repetitions of a rubbing motion. Cleaning of the fiber ends, after polishing, may be required, using conventional cleaning materials and methods, including liquid spray cleaning, to remove accumulated debris that could obscure the fiber end face causing optical signal attenuation. Thereafter, pivoting the guide plate, unlatching the hinged lid, lifting the jacketed cable and fiber holder, and separating the two main parts of the temporary holder releases the stripped, cleaved and polished optical fibers from the puck.  
       [0018] Field assembly of a connector plug involves the relatively simple process of inserting one or more optical fibers into one side of crimp elements. The crimp elements have limited movement in elongate depressions formed in the floor of the molded base of any one of several embodiments of connector plugs according to the present invention. Connector plugs may be used with single optical fibers, but preferably the plug has a design to accommodate two or more optical fibers. Most preferably the plug may be used as a duplex plug, for two optical fibers contained in a single-jacketed cable. Each optical fiber enters its assigned crimp element to the point at which it contacts the cleaved and polished face of an optical fiber stub that was factory installed at the opposite end of the crimp element. A crimp element has a size and internal design to provide accurate alignment, orientation and facial contact between each newly cleaved optical fiber end and each optical fiber stub. Interfacial contact for optimum signal transmission through multi-fiber connector plugs relies upon the equal length of the optical fiber terminal portions, having slightly angled, cleaved and polished end faces, and the precise positioning of the crimp elements within the connector plug. After achieving the desired positioning and alignment, the newly cleaved fiber ends may be secured in the crimp elements using a crimping tool, also referred to herein as a compression cap.  
       [0019] Optical signal transmission relies upon accurate alignment full surface contact of the slightly angled ends of optical fibers and optical fiber stubs spliced together using crimp elements as described previously. Other features of connector plugs according to the present invention facilitate insertion of one or more optical fibers into the body of a connector plug and allow component size reduction, which results in optical fiber cable installations requiring less space or containing increased numbers of plug and socket connections.  
       [0020] More particularly the present invention provides an article for temporarily retaining an optical fiber cable including a stripped terminal portion of at least one optical fiber requiring cleaving followed by polishing of an end face thereof. The article comprises a housing having a recess for a demountable optical fiber holder. A demountable optical fiber holder includes a base-plate having at least a first fiber channel formed therein to receive the stripped portion of the at least one optical fiber. The base plate has a number of pockets. A cover plate for the demountable optical fiber holder includes a spring clamp, at least a first upper channel and a number of posts to mate with the pockets of the base-plate to assemble the demountable optical fiber holder. The article further includes a guide plate attached at the distal end of the housing to pivot between a first pivot position and a second pivot position. The guide plate has at least one opening for the stripped portion of the at least one optical fiber. A rotatable lid attached to the housing rotates between an open position and a closed position. The lid includes a latch and a pressure bar, with the latch engaging the housing to bias the pressure bar against the spring clamp to hold the optical fiber immobile between the spring clamp and at least the first fiber channel when the demountable holder resides in the recess. The article temporarily retains the optical fiber cable for cleaving and polishing the end face thereof when the lid is closed.  
       [0021] The present invention also provides an optical fiber connector plug for mating with an optical fiber receptacle to form an optical fiber connection. The optical fiber connector plug comprises a connecting portion comprising a containment body including a rear entry at a first end and a first fiber stub exit opening to a first fiber stub channel. The first fiber stub exit is parallel to a second fiber stub exit opening to a second fiber stub channel. The first and second fiber stub exits are formed at a second end opposite the first end of the containment body. The rear entry divides at a junction into a first fiber groove and a second fiber groove that diverges from the first fiber groove. The containment body includes first and second crimp elements each having an open-ended bore coaxial with the first and second fiber grooves. Each crimp element contains a optical fiber stub. A molded top attached to the containment body includes a substantially rectangular opening. The opening contains a compression element that moves between a first position and a second position to apply force to the first crimp element and the second crimp element. In its first and second positions the compression element first adjusts each bore and then forms splices by capturing a stripped, cleaved and polished end portion of an optical fiber and an optical fiber stub in each of the crimp elements. A bend relief boot encloses the connecting portion at one end, while a shroud releasably engages it at the other end.  
       [0022] The present invention further provides an optical fiber connector plug for mating with an optical fiber receptacle to form an optical fiber connection. The optical fiber connector plug comprises a connecting portion comprising a containment body including a rear entry at a first end and a first fiber stub exit opening to a first fiber stub channel. The first fiber stub exit is parallel to a second fiber stub exit opening to a second fiber stub channel. The first and second fiber stub exits are formed at a second end opposite the first end of the containment body. An optical fiber connector plug according to the present invention includes a holder for permanent retention of at least one stripped, cleaved and polished end portion of a an optical fiber. The holder has a size for insertion into the rear entry of the containment body. The containment body includes first and second crimp elements each having an open-ended bore coaxial with the fiber stub channels. Each crimp element contains a optical fiber stub. A molded top attached to the containment body includes a substantially rectangular opening. The opening contains a compression element that moves between a first position and a second position to apply force to the first crimp element and the second crimp element. In its first and second positions the compression element first adjusts each bore and then forms splices by capturing a stripped, cleaved and polished end portion of an optical fiber and an optical fiber stub in each of the crimp elements. A bend relief boot encloses the connecting portion at one end, while a shroud releasably engages it at the other end.  
       [0023] According to the present invention a process may be used for field terminating at least one optical fiber in an optical fiber connector plug. The process comprises a number of steps including providing an article for retaining an optical fiber cable. The article comprises a housing having a recess for an optical fiber holder. The article further includes a guide plate attached at the end of the housing to pivot between a first pivot position and a second pivot position. The guide plate has at least one opening for a stripped portion of at least one optical fiber. A rotatable lid attached to the housing rotates between an open position and a closed position. The article temporarily retains the optical fiber cable for cleaving and polishing the end face of the optical fiber when the lid is closed. The guide plate engages a cleaving device for cleaving at least one optical fiber. This is followed by polishing the end face of the at least one cleaved fiber end to provide a stripped, cleaved and polished end portion of at least one optical fiber. Removal of the optical fiber cable and the demountable optical fiber holder from the article precedes release of the stripped, cleaved and polished end portion of the at least one optical fiber from the optical fiber holder. The optical cable is then terminated by inserting the stripped, cleaved and polished end portion of at least one optical fiber into an optical fiber connector plug that has a connecting portion using crimp elements to splice the stripped, cleaved and polished end portions of optical fibers to optical fiber stubs located at the front of a connector plug. After completing splices applying a bend relief boot to enclose one end of the connecting portion and engaging a shroud over the other end provides at least one optical fiber terminated by an optical fiber connector plug according to the present invention. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0024] Notwithstanding any other forms, which may fall within the scope or the present invention, preferred forms of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:  
     [0025]FIG. 1 is a schematic plan view showing an apparatus, referred to herein as a puck that contains optical fibers during cleaving and polishing.  
     [0026]FIG. 2 is a plan view showing a fiber receiving plate of an optical fiber holder having a pair of stripped optical fibers positioned therein.  
     [0027]FIG. 3 is a plan view of a cover plate of an optical fiber holder according to the present invention.  
     [0028]FIG. 4 is a plan view showing an optical fiber holder assembled to contain at least one optical fiber.  
     [0029]FIG. 5 is a perspective view of an apparatus, used to contain optical fibers during cleaving and polishing, showing positioning of an optical fiber holder and jacketed optical fiber cable.  
     [0030]FIG. 6 is a cross sectional side view showing the closed and latched position of an apparatus used to contain optical fibers during cleaving and polishing.  
     [0031]FIG. 7 is an exploded perspective view of one embodiment of a connector plug designed to contain optical fibers.  
     [0032]FIG. 8 is a perspective view of a connector plug according to the present invention.  
     [0033]FIG. 9 is an exploded perspective view of a second embodiment of a connector plug including an insertion slot to facilitate positioning of optical fibers in the connector plug body.  
     [0034]FIG. 10 is a perspective view of a pre-assembled connecting portion of a connector plug according to the present invention.  
     [0035]FIG. 11 is a schematic plan view of a pre-assembled connecting portion of a connector plug including an insertion slot and pre-installed optical fiber stubs.  
     [0036]FIG. 12 provides a schematic plan view of a fiber containment body of a connector plug showing relative positioning of a compression element and crimp elements used to form crimp splices during termination of optical fiber cables.  
     [0037]FIG. 13 is a cutaway perspective view showing a pre-assembled connecting portion of a connector including a latch to retain the connector plug in contact with the connector receptacle of an optical fiber connecting assembly.  
     [0038]FIG. 14 is an exploded perspective view of a third embodiment of a connector plug including a fiber positioner to facilitate positioning of optical fibers in a connector plug body.  
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
     [0039] The following description provides information of several varieties of optical fiber connector plugs and an apparatus, referred to herein as a puck, for use in cleaving and polishing ends of stripped optical fibers to be installed in selected connector plugs. In each case, the puck and connector plugs are adapted particularly for field use and assembly to facilitate convenient custom installation of optical cable networks. Optical fiber connector plugs, described herein, are of the type that use V-grooves to position and align terminal portions of the optical fibers. Figures presented herein are not necessarily to scale, some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention.  
     [0040] Referring now to the figures wherein like numbers refer to like parts throughout the several views, FIG. 1 is a schematic plan view showing an article referred to in the industry as a puck  10  or polishing puck for use with an optical fiber cleaving and polishing apparatus. The puck  10  is shown in its open position. It includes a housing  12  sized to receive a multi-fiber cable  14  prepared for cleaving of one or more stripped optical fibers  16 . Optionally, the puck  10  may be designed to contain single jacketed fibers or several jacketed fibers placed side by side in the puck  10 . Preparation of the cable  14  requires removal of optical fiber sheath and buffer layers from each optical fiber  16  contained by the optical fiber cable  14 . Removal of the protective sheath and buffer layers exposes stripped optical fibers  16  having sufficient length for insertion into an optical fiber holder  18  so that the optical fibers  16  pass through fiber channels  34 ,  36  (see FIG. 2) and protrude from the other side of the fiber holder  18  until the outer jacket of the cable  14  abuts a cable stop  44  (see FIG. 3) in the entry port  20  of the holder  18 . In an optional embodiment of the holder  18 , the fiber channels  34 ,  36  vary in width along their length in such a way that the a proximal portion of the fiber channels  34 ,  36 , adjacent to the sheathed cable  14 , has a width sufficient to accommodate a buffer covered optical fiber  16 . Beyond the proximal portion, a distal portion of the fiber channels  34 ,  36  narrows to only the width of an optical fiber  16  that has been stripped of both sheath and buffer layers. The transition point between the proximal and distal portions of the fiber channels  34 ,  36  forms a buffer stop preventing movement of optical fibers  16  through the fiber channels  34 , 36  of the holder  18  when the lead edge of a buffered optical fiber  16  encounters the buffer stop. An optional transition plate, machined or molded to provide a buffer stop, may be joined to the end of the holder  18 , opposite the entry port  20 , so that it aligns with the fiber channels  34 ,  36 . Correct positioning of optical fibers  16  in the holder  18  may be achieved, during threading of optical fibers  16 , by interference of the jacketed cable with the cable stop  44 , by contact of buffer covered fibers  16  with buffer stops, or by the combined effect of both.  
     [0041] After preparation for temporary attachment of the two-part optical fiber holder  18 , the optical fiber cable  14  may be installed resting on a resilient pad  21  in an opening  22  in the housing  12 . In FIG. 1 the fiber holder  18  occupies a recess (not clearly shown) adjacent to a guide plate  24  having a size and shape for orientation of the puck  10  in a cleaving and polishing apparatus used to produce end-polished optical fibers  16  of precisely cleaved length. It is important that the cable  14  and optical fiber holder  18  be held in a fixed position during cleaving of the optical fibers  16 . For this purpose a rotatable lid  26 , attached to the housing  12  by a hinge  28 , closes over the housing  12  so that the cable  14  and optical fiber holder  18  become immovably trapped between the lid  26  and the housing  12 .  
     [0042]FIG. 2 shows the structure of the base-plate  30  of a two-part, demountable optical fiber holder  18 . The base-plate includes the lower half  32  of the cable entry port  20  that provides access to a first fiber channel  34  and a second fiber channel  36 . When installed in the optical fiber holder  18 , stripped optical fibers  16  are separated into individual strands that each have sufficient length to occupy one of the channels  34 ,  36  and extend beyond the end of the holder  18  opposite the entry port  20 . The base-plate  30  includes a number of pockets  38  to facilitate sliding engagement of a cover-plate  40  with the base-plate  30 .  
     [0043]FIG. 3 shows the structure of the underside of a cover-plate  40  that is the second part of a demountable optical fiber holder  18  according to the present invention. The cover-plate  40  includes the upper half  42  of the entry port  20  that has a cable stop  44  to limit the amount of the jacket of the optical fiber cable  14  that enters the assembled fiber holder  18 . A first upper channel  46  and a second upper channel  48  have axial alignment with the first fiber channel  34  and the second fiber channel  36  to enclose the stripped optical fibers  16  when the cover-plate  40  engages the base-plate  30 . Engagement of these two parts  30 ,  40  occurs when posts  50  slide into the pockets  38  in the base-plate  30  to produce an assembled optical fiber holder  18 . An important feature of an optical fiber holder  18  according to the present invention is a spring clamp  52  integrally formed with the cover-plate  40  to flex towards the optical fibers  16  to immovably clamp them in the fiber channels  34 ,  36  during application of a biasing force. As illustrated in FIG. 3, the spring clamp  52  is a T-shaped cantilever that includes a fiber contact bar  53  on one surface and a compression bar  54  (see FIG. 4) on the surface opposite the contact bar  53 .  
     [0044]FIG. 4 shows an assembled optical fiber holder  18  applied to an end of an optical fiber cable  14  with stripped optical fibers  16  protruding from the optical fiber holder  18 . Although described previously with reference to the separated components, the optical fiber holder  18  is typically assembled and placed in the recess of the puck  10  before threading the stripped fibers  16  through the holder  18 .  
     [0045] The process of attaching a fiber holder  18  to an optical fiber cable  14  requires first removal of the jacket from the cable  14  followed by stripping of the sheath and buffer from a length of each individual optical fiber  16  that exceeds the length dimension of the optical fiber holder  18 . Stripped optical fibers  16  reach their positions inside the fiber holder  18  by inserting the optical fibers  16  into the entry port  20  of an assembled holder  18  and gently guiding them through the channels  34 , 48 ;  36 , 46  so that they pass the spring clamp  52  to protrude beyond the end of the holder  18 . Movement of the optical fibers  16  through the channels  34 , 48 ;  36 , 46  ceases when the jacket of the multi-fiber cable  14  encounters the cable stop  44  inside the cable entry port  20 , or the buffered fiber encounters the buffer stop. Consistent positioning of the optical fiber cables  14  against the cable stop  44  (see FIG. 3) or buffer stop results in cleaving of stripped optical fibers  16  to precise, consistent length.  
     [0046]FIG. 5 is a perspective view showing the relative positioning of an optical fiber holder  18  and the terminal portion of an optical fiber cable  14  inside the housing of a puck  10  according to the present invention. The optical fiber holder  18  fits into a recess (not clearly shown) and the cable  14 , extending from the fiber holder entry port  20 , rests against a resilient pad  21  residing in the opening  22  to support the optical fiber cable  14 . Stripped optical fibers  16 , extending from the optical fiber holder  18 , protrude through openings in the guide plate  24  in a position for cleaving level with the front surface of the guide plate  24  after latching of the lid  26  of the puck  10 . Pressure applied to the compression bar  54  of the spring clamp  52  will move the contact bar  53  (not shown) into a gripping relationship with the optical fibers  16  holding them in a fixed position during cleaving.  
     [0047] The rotatable lid  26  includes a pressure bar  56  and a pressure plate  58  that apply pressure against the optical fiber holder  18  and the optical fiber cable  14  when the lid  26  is rotated about the hinge  28  for latching against the housing  12 . Any number of latching mechanisms may be used to effectively retain the rotatable lid  26  in contact with the housing  12 . As illustrated, in FIG. 5, a latch  60  includes an elongate bar having a hooked edge  62 . In its fully closed position, the hooked edge  62  of the rotatable lid  26  grips ledge segments  64  molded into the housing  12  of the puck  10 . The pressure bar  56  and the pressure plate  58  of the closed and latched lid  26  exert pressure against the compression bar  54  of the spring clamp  52  and optical fiber cable  14  respectively in such a way that the cable  14  becomes immobilized between the pressure plate  58  and the pad  21  and the stripped optical fibers  16  become fixed in the fiber channels  34 ,  36  using the force transmitted from the compression bar  54  through the spring clamp  52  to the contact bar  53 .  
     [0048]FIG. 6 is a side cross sectional view showing a puck  10  in its closed position wherein a terminal portion of an optical fiber cable  14  and a demountable optical fiber holder  18  have been releasably secured in preparation for cleaving the excess length from the optical fibers  16  protruding from the openings in the guide plate  24  of the puck  10 .  
     [0049] The process of cleaving and polishing, described below, is presented in greater detail in U.S. Pat. No. 6,099,392 that is commonly owned with the present application. One result of the cleaving and polishing process is the production of polished end faces on multiple optical fibers of which the stripped terminal portions have been cleaved to be of equal length. A puck  10  or polishing puck according to the present invention uses the guide plate  24  as a mating component that seats in a pair of opposing tracks of an optical fiber cleaving and polishing device described in U.S. Pat. No. 6,099,392. Between the guide tracks, a groove provides space to accommodate the excess lengths of optical fiber  16  extending from the openings in the guide plate  24  when it slides in the tracks. As the polishing puck  10  slides along the guide tracks it approaches and contacts a sharpened edge where cleaving of the fibers  16  occurs. The guide tracks of the cleaving and polishing device extend a short distance beyond the sharpened edge before releasing the puck  10 . This maintains the orientation of the guide plate  24  for a short distance beyond the point of cleaving of the fibers  16 .  
     [0050] It is known that several measurable parameters of an optical fiber end face affect the quality of signal transmission of an optical fiber connection. Such parameters include the angle of the optical fiber end face and its planarity and surface smoothness. End-face angle is important for full face-to-face contact between spliced or connected optical fibers. Surface roughness and lack of surface planarity also interfere with contact between end faces of spliced or connected optical fibers.  
     [0051] Earlier evidence suggested the need for an end face at an angle of 90° to the optical fiber axis. According to the present invention, after satisfying planarity and surface smoothness requirements, a further improvement of signal transmission is possible when the angle of the end face to the optical fiber axis is slightly more than 90°. Expressed in terms of angular deviation from perpendicular to the fiber axis, evidence shows that an end face angle less than about 10° and preferably 8° provides signal improvement with less attenuation. End face angle adjustment depends upon the construction of the puck  10  used for preparing terminal portions of stripped optical fibers  16  according to the present invention. Referring to FIG. 6, the guide plate  24  is attached to pivot relative to the housing  12  using a pivot mechanism that includes a hook  25  in frictional contact with a pivot post  27 . The pivot mechanism allows movement of the guide plate  24  between a closed position, as shown in FIG. 6, and an open position in which the guide plate  24  releases the optical fiber ends from the openings they occupied during cleaving and polishing. In its closed position, the angle of the guide plate  24  to the axis of the optical fibers  16  differs from perpendicular by the desired amount less than 10°. Positioning of the guide plate  24  in the guide tracks, of the cleaving and polishing device, determines the angle between the optical fibers  16  and the sharpened edge at the point of cleavage. It will be appreciated that the angle of cleavage can be changed depending on the position and angle of the guide plate  24  to the axis of the optical fibers  16 .  
     [0052] After passing the sharpened edge and releasing from the guide tracks of the cleaving device, the exposed surface of the guide plate  24  stabilizes the orientation of the cleaved end faces of the optical fibers  16  against a lapping surface provided with the cleaving and polishing device. Movement of the puck  10  against the lapping surface, using several strokes of a pre-determined pattern, causes smoothing and polishing of the cleaved end faces of the optical fibers  16 .  
     [0053] Completion of the cleaving and polishing process provides one or more optical fibers  16  of prescribed length and having a polished end face. The puck  10  contains a pair of optical fibers  16  that have been prepared to have equal length. Thus prepared, the optical fibers  16  may be released from the openings in the guide plate  24  by pivoting the guide plate  24  away from the housing  12 . The cable  14  may be removed from the puck  10 , with the holder  18  attached, after the lid  26  has been unlatched and rotated away from the housing  12 . With removal of the jacketed cable from the resilient pad  21 , the holder  18  may be lifted out of the recess. The cover plate  40  may be separated from the base-plate  30  of the demountable holder  18  by withdrawing the posts  50  of the cover plate  40  from the pockets  38  formed in the base plate  30 . This provides a jacketed optical fiber cable  14  having an end portion from which the jacket was removed for preparation of bare end portions of optical fibers  16  that, after preparation by cleaving and polishing, are of substantially equal length and have polished end faces for substantially full-face contact with end faces of pre-installed optical fiber stubs in e.g. connector plugs according to the present invention.  
     [0054]FIG. 7 provides an exploded perspective view of an optical fiber connector plug  70  according to the present invention including a terminal portion of an optical fiber cable  14  showing two stripped, cleaved and polished optical fibers  16  of selected, equal length as they would appear following preparation using a puck  10  and a cleaving and polishing device, as described previously. The use of fibers  16  of equal length provides the key to field assembly of optical fiber connector plugs  70  for optimum signal transmission. A molded connecting portion  72  includes additional features and components that further increase the probability of optimal field assembly of a connector plug  70  according to the present invention. A connecting portion  72  comprises a fiber containment body  74  including a structured floor  76  having a rear entry  78 , extending to a junction  80  of a first fiber groove  82  and a second fiber groove  84 . The grooves  82 ,  84  have a height slightly greater than the diameter of a buffer coated optical fiber  16  and extend on diverging paths into a central region of the fiber containment body  74  before terminating at a first elongate depression  85  and a second elongate depression  87 , which act as seats for a first crimp element  86  and a second crimp element  88  respectively. Each of the crimp elements  86 ,  88  has limited movement in an elongate depression  85 ,  87  in the floor  76  of the fiber containment body  74 . Correct positioning in each elongate depression  85 ,  87  provides alignment of the longitudinal axes of the crimp elements  86 ,  88  and the respective grooves  82 ,  84  used to guide the optical fibers  16  into the crimp elements  86 ,  88 .  
     [0055] The end of the fiber containment body  74  opposite the rear entry  78  includes a first fiber stub exit  90  parallel to and separated from a second fiber stub exit  92 . Each fiber stub exit  90 ,  92  accommodates a factory installed optical fiber stub  94 ,  96  inserted into a stub channel  95 ,  97  that leads to the front end  98 ,  100  of a crimp element  86 ,  88 . After insertion of equal amounts of fiber stubs  94 ,  96  into the front ends  98 ,  100  of the crimp elements  86 ,  88 , approximately one half of the length of the bore of each of the crimp elements  86 ,  88  contains a portion of an optical fiber stub  94 ,  96  adhesively secured in an adhesive open-ended tray  99  adjacent to the front ends  98 ,  100  of the crimp elements  86 ,  88 .  
     [0056] A molded top  110  placed over the fiber containment body  74  completes a pre-assembled connecting portion  72  prepared for insertion of the cleaved and stripped end portions of an optical fiber cable  14 . The underside of the molded top  110  has no fiber channels matching those  82 ,  84  formed in the fiber containment body  74 . A rectangular hole  112  in the molded top  110  accommodates a compression element  114  designed to close the crimp elements  86 ,  88  between their front ends  98 ,  100  and rear ends  102 ,  104  during the formation of crimp splices of optical fibers  16  to optical fiber stubs  94 ,  96 . The compression element  114  occupies two positions relative to the crimp elements  86 ,  88 . In its first or fiber-load position the compression element  114  passes through the rectangular hole  112  into a gripping relationship with the crimp elements  86 ,  88  to narrow the bore of each crimp elements  86 ,  88 . Narrowing of the bore of each crimp element  86 ,  88  provides enough space for sliding entry of the ends of the optical fibers  16  but prevents escape of the optical fibers  16  through the side openings of the crimp elements  86 ,  88 . Application of force moves the compression element  114  to its second or crimp position further inside the rectangular hole  112 . Raised features on the inner face of the compression element  114  apply a lateral force to the sides of the crimp elements  86 ,  88  as the compression element  114  moves to its crimp-position. Application of lateral force further narrows the bore of each crimp element  86 ,  88  to form a crimped splice that secures the ends of the optical fibers  16  and the fiber stubs  94 ,  96  so that there is coaxial alignment and full-face contact between these components. The resulting crimped splice resembles that formed using crimp elements commercially available from 3M Company, St. Paul, Minn. under the trade name FIBRLOK™. Further description of crimp elements of this type exists in U.S. Pat. No. 5,638,477 and related patents that are commonly owned with the present application.  
     [0057] A rectangular trough  116 , formed in the molded top  110 , provides a seat for a biasing element  120  and surrounds an adhesive injection port  118  formed through a shroud catch  119 . Adhesive, injected through the injection port  118 , accumulates in the open-ended tray  99  to adhesively secure portions of the fiber stubs  94 ,  96  that pass the ends of open-ended tray  99  and become bonded by the adhesive as it cures during exposure to ultraviolet radiation. The biasing element  120  resists bending of the optical fiber stubs  94 ,  96  during insertion of an optical fiber connector plug  70  into a mating socket (not shown) to form a face-to-face optical fiber connection that introduces a compressive force at the fiber-to-fiber interface.  
     [0058] A molded connecting portion  72 , shown in FIG. 7 in exploded view, is normally factory assembled to include optical fiber stubs  94 ,  96  secured, as described previously, using a photocurable adhesive injected into the open-ended tray  99  adjacent to the front ends  98 ,  100  of the crimp elements  86 ,  88 . Factory assembly using an interlocking mechanism to secure molded tops  110  to fiber containment bodies  74  provides connecting portions  72  offering not only field termination of optical fiber cables, but including preferred optical fiber stubs  94 ,  96 , fabricated using GGP (glass/glass/polymer) fibers, that have greater resistance to bending fracture than ordinary optical fibers. Regardless of the type of optical fiber used in optical fiber network cables, a plug and socket connection benefits from the use of GGP optical fiber stubs  94 ,  96  even though the crimp splice inside the connecting portion  72  of a connector plug  70  includes other optical fibers  16 , i.e. non-GGP fibers, from the optical fiber cable  14 . As supplied for attaching to a terminal portion of an optical fiber cable  14 , the molded connecting portion  72 , resides inside a two-part enclosure  122 .  
     [0059]FIG. 8 provides a perspective view of a two-part enclosure  122  according to the present invention including a bend relief boot  124  and protective shroud  126 . Before inserting cleaved and polished optical fibers  16  into the connecting portion  72  of the optical fiber connector plug  70 , the bend relief boot  124 , supplied with a connector plug  70  assembly kit, is placed around the optical fiber cable  14 , as shown in FIG. 7. Holding the stripped optical fibers  16  between thumb and forefinger, an installer introduces slight diverging separation between the fibers  16  and then inserts them into the rear entry  78  of the molded connecting portion  72 . Slight diverging separation of the optical fibers  16  is needed to assist entry of the fibers  16  into one of the first  82  or second  84  fiber grooves. Correctly positioned fibers  16  adopt the same V-shaped relationship as the grooves  82 ,  84  into which they are inserted. Care is required while threading the stripped optical fibers past the junction  80  to prevent cross-over of the optical fibers  16  placing them in an X-shaped relationship and misdirecting light signals passing through an optical fiber connector plug  70  of this type. After successful insertion of optical fibers  16  in the fiber grooves  82 ,  84  the optical fiber cable  14  enters the rear entry  78  and the end of each optical fiber  16  extends into the first  102  and second  104  rear ends of the crimp elements  86 ,  88  making face-to-face contact with the faces of the optical fiber stubs  94 ,  96  already securely positioned in the front ends  98 ,  100  of the crimp elements  86 ,  88 . Final connection of the optical fibers  16  requires application of downward force to the compression element  114  to secure the optical fibers inside the crimp elements  86 ,  88 . Upon completion of the splice between the stripped optical fibers  16  and the optical fiber stubs  94 ,  96 , adhesive, injected through the injection orifice  121 , bonds the KEVLAR™ fiber layer  123  of the optical cable  14  to the wall of the rear entry  78  to provide strain relief. The bend relief boot  124  may then be slid forward along the optical fiber cable  14  to grip and enclose a portion of the connecting portion  72  corresponding to the boundary with the front ends  98 ,  100  of the crimp elements  86 ,  88 . Final assembly of the connector plug  70  requires attachment of the protective shroud  126  by engagement between the shroud aperture  117  and the shroud catch  119  to provide the two-part enclosure  122  that protects the connecting portion  72 .  
     [0060]FIG. 9 provides an exploded perspective view of a second embodiment of an optical fiber connector plug  270  according to the present invention including a molded connecting portion  272  that includes additional features to further increase the probability of optimal field assembly of a connector plug  270  according to the present invention. A connecting portion  272  comprises a fiber containment body  274  including a structured floor  276 . The structured floor  276  has essentially the same features as the previously described structured floor  76  including a rear entry  78 , extending to a junction  80  of a first fiber groove  82  and a second fiber groove  84  and first  86  and second  88  crimp elements. In addition to these features, the fiber containment body  274  further includes a tapered wall  277 , molded into the floor  276  between the first fiber groove  82  and the second fiber groove  84 , to prevent crossover of optical fibers  16 , thereby directing them towards the correct crimp elements  86 ,  88  for maintaining optical signal integrity.  
     [0061] Other features in common with the previously described fiber containment body  74  include a first fiber stub exit  90  parallel to and separated from a second fiber stub exit  92 . Each fiber stub exit  90 ,  92  accommodates a factory installed optical fiber stub  94 ,  96  inserted through a stub channel  95 ,  97  for precise positioning, into the front end  98 ,  100  of a crimp element  86 ,  88 . As before, after insertion of equal amounts of fiber stubs  94 ,  96  into the front ends  98 ,  100  of the crimp elements  86 ,  88  approximately one half of the length of the bore of each of the crimp elements  86 ,  88  contains a portion of an optical fiber stub  94 ,  96  adhesively secured at the ends of an open-ended tray  99  adjacent to the front ends  98 ,  100  of the crimp elements  86 ,  88 .  
     [0062] A molded top  210  placed over the fiber containment body  274  completes a pre-assembled connecting portion  272  prepared for insertion of cleaved and stripped end portions of an optical fiber cable  14 . As described previously, an interlocking mechanism provides secure attachment of a molded top  210  to a fiber containment body  274 . FIG. 9 clearly shows components used to interlock a molded top  210  with a fiber containment body  274 . The interlocking mechanism includes barbs  212  on opposing sides at the front of the top  210  that engage projections  214  on the fiber containment body  274  to position clasps  216  at the rear of the top  210  so that they interlock with through-holes  218  as the molded top  210  folds down toward the containment body  274 .  
     [0063] The molded top  210  includes the substantially rectangular hole  112  to accommodate a compression element  114  that closes the crimp elements  86 ,  88  during the formation of crimp splices between optical fibers  16  and optical fiber stubs  94 ,  96 . A rectangular trough  116 , formed in the molded top  210 , surrounds an injection port  118  and provides a seat for a biasing element  120  used to restrict movement of the optical fiber stubs  94 ,  96  after insertion of a connector plug  270  into a connector receptacle (not shown).  
     [0064] Although similar to the molded top  110  described above, the molded top  210  of the second embodiment of an optical fiber plug  270  further includes a longitudinal slot  278  extending from the rear entry  78  approximately to the middle of the molded top  210 . The slot  278  provides better access to the grooves  82 ,  84 , overcoming the possibility that fibers  16  inserted through the rear entry  78  will cross over as they pass the junction  80 . Optical fibers  16 , placed in the slot  278 , encounter the tapered wall  277  that protrudes into the slot  278  to keep the fibers  16  separated and directed towards the grooves  82 ,  84  for crimp splice formation to ensure optical signal integrity. Installation of stripped optical fibers  16  in the slot  278  preferably involves gripping the fibers  16  between thumb and forefinger, as before, so that the fibers  16  diverge slightly from each other. This facilitates placement of the optical fibers  16  in the slot  278  and on either side of the tapered wall  277 . After placing the stripped optical fibers  16  in their respective grooves  82 ,  84 , the jacketed portion of the optical fiber cable  14  may be moved towards the rear entry  78  so that the optical fibers  16  slide forward into the crimp elements  86 ,  88  and take up the desired position abutting the ends of the optical fiber stubs  94 ,  96 . The distance between the point of insertion of the optical fibers  16  and the crimp elements  86 ,  88 , in this embodiment of an optical fiber connector plug, is less than for the embodiment discussed previously. This is an added benefit, which lowers the possibility of unprotected, bare ends of the optical fiber  16  becoming damaged and chipped by inadvertent contact with the walls of the fiber grooves  82 ,  84  during insertion of the optical fibers  16  for splicing.  
     [0065]FIG. 10 and FIG. 11 provide a perspective view and schematic plan view respectively of a pre-assembled connecting portion  272  prepared for insertion of cleaved and stripped end portions of an optical fiber cable  14 . Using this version of a connecting portion  272  of a connector plug  270  according to the present invention, the tips of cleaved and polished optical fibers  16  may be positioned above the tapered wall  277  and lowered into the slot  278  so that they fall on either side of the tapered wall  277 . Thus separated, the optical fibers  16  maintain the divergent relationship needed for accurate placement of the stripped optical fibers  16  in the fiber grooves  82 ,  84 . Using the fiber cable  14  to move the optical fibers  16  further into the connecting portion  272 , the tips of the optical fibers  16  follow the fiber grooves  82 ,  84  before entering the crimp elements  86 ,  88 . Resistance to further movement indicates that there is abutment between the end faces of the optical fibers  16  and the fiber stubs  94 ,  96 . Movement of the compression element  114  from its fiber-load position to its crimp position captures the ends of the optical fibers  16  and the fiber stubs  94 ,  96  to provide a crimp splice as described previously. As before, formation of an adhesive bond between the KEVLAR™ fibers  123  of the optical fiber cable  14  and the walls of the rear entry  78  of the connecting portion  272  provides strain relief between the cable  14  and a connector plug  270  according to the present invention.  
     [0066]FIG. 12 is a schematic diagram of a fiber containment body  274  of a connector plug  270  showing the relative locations of the end of the jacketed cable  14 , the stripped optical fibers  16  and particularly the relationship of the compression element  114  to the crimp elements  86 ,  88 . As illustrated, the end of the optical fiber cable  14  occupies the rear entry  78  of the fiber containment body  274  with terminal portions of the stripped optical fibers  16  residing in the first fiber groove  82  and the second fiber groove  84  and extending into the crimp elements  86 ,  88  after diverging by separation at the tapered wall  277 . Application of pressure to the compression element  114  produces a crimp splice between each optical fiber  16  and its respective factory installed fiber stub  94 ,  96 . The diagram of FIG. 12 shows that the compression element  114  applies force to form crimp splices between the front ends  98 ,  100  and rear ends  102 ,  104  of the crimp elements  86 ,  88 .  
     [0067]FIG. 13 provides a perspective cut-away view taken through line  13 - 13  of FIG. 11 to show a factory assembled connecting portion  272  of a connector plug  270  according to the present invention. As illustrated, the compression element  114  is in its fiber-load position that allows the terminal portions of optical fibers  16  to enter the crimp elements  86 ,  88  unimpeded. This view also reveals a plug latch  280  used as a means for retaining a connector plug  270  in secure mating relationship with a connector receptacle.  
     [0068]FIG. 14 provides an exploded perspective view of a third embodiment of an optical fiber connector plug  370  suitable for field installation in situations where termination of an optical fiber cable  14  does not require installer dexterity associated with feeding stripped terminal portions of optical fibers  16  into channels  82 ,  84  or a slot  278  formed in preassembled connecting portions  72 ,  272  described previously. Instead, an installer has the option of field terminating one or more optical fibers  16  by applying a permanent fiber positioner  380  that may be used with a polishing puck  10  in place of the demountable, temporary optical fiber holder  18  described above. A permanent fiber positioner  380  includes a base-plate  330  connected to a cover-plate  340  in such a way that the positioner  380  is difficult to re-open after preparing the cable  14 , to remove sheath and buffer layers and inserting the terminal portions of optical fibers  16  through channels in the positioner  380  and openings in the puck guide plate  24 . After preparation for substantially permanent attachment of the two-part fiber positioner  380 , the optical fiber cable  14  may be installed in the puck  10 , immobilized therein after latching the rotatable lid  26  (see e.g. FIG. 5 or FIG. 6). Cleaving and polishing of the terminal portions of the optical fibers  16 , protruding from the face of the guide plate  24 , proceeds with the optical fibers held immobile using the optical fiber positioner  380 . The cleaving and polishing device and process, in this case, is no different to those used with the temporary holder  18  that was illustrated in e.g. FIG. 5. As before the cleaving and polishing process is capable of producing multiple fibers of equal length for insertion into a connecting section  372  of a connector plug  370  according to the present invention.  
     [0069] The cable  14  may be removed from the puck  10 , with the optical fiber positioner  380  attached, after the lid  26  has been unlatched and rotated away from the housing  12 . With removal of the jacketed cable from the resilient pad  21 , the fiber positioner  380  may be lifted out of the recess and retained on the end of the optical fiber cable  14 . This maintains a parallel relationship between the terminal portions of optical fibers  16  before insertion into the molded connecting portion  372  of a connector plug  370 . Adhesive, injected through a bonding port  321  bonds KEVLAR™ strands (not shown), surrounding the sheathed optical fibers  16 , to the optical fiber positioner  380  to provide strain relief for the optical fiber cable  14 .  
     [0070] A molded connecting portion  372  includes features for optimal field assembly of a connector plug  370  according to the present invention. A connecting portion  372  comprises a fiber containment body  374  including a structured floor  376 . A factory pre-assembled connecting portion  372  includes, as before, adhesively bonded GGP optical fiber stubs  94 ,  96 . In this embodiment the rear entry  378  has been modified to accommodate the fiber positioner  380  that pre-positions the stripped optical fibers  16  in parallel relationship. Also, in this embodiment there is no need for a junction or diverging fiber grooves because the optical fibers  16 , held parallel by the fiber positioner  380 , have the required alignment to feed directly into the crimp elements  386 ,  388  that now have a parallel relationship to one another in corresponding elongate depressions  385 ,  387 . In common with earlier embodiments of the present invention, a compression element  114  operates between a fiber-load position and a crimp position to adjust the bore size of each crimp element  386 ,  388  for formation of a splice of the optical fibers  16  in abutment with the fiber stubs  94 ,  96 . After inserting an optical fiber positioner  380  in the rear entry  378 , and actuating the compression element  114  to its splice-forming crimp position, the bend relief boot  124  and shroud  126  may be moved into position to enclose the connecting portion  372  and complete the field assembly of the connector plug  370 . The size of the optical fiber positioner  380  requires an increase in the overall size of this embodiment of a connector plug  370 , which may be a disadvantage compared to earlier embodiments of the present invention. Regardless of size, this version of a connector plug  370  is useful for facilitating field termination of optical fiber cables.  
     [0071] As required, details of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary and not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention.