Abstract:
The invention provides an optical connector for coupling a plurality of optical fibers in an array configuration. The optical connector housing is designed to accommodate a plurality of array ferrules. Each array ferrule holds multiple fiber ends each being precisely positioned with respect to alignment features of the ferrule. The plurality of ferrules may be either independently biased or dependently biased.

Description:
BACKGROUND 
     This invention is related to optical connectors and more particularly to an optical connector having a plurality of optical array interfaces. 
     Over the past two decades the requirements for data transmission have doubled approximately every two years. The Internet and other computer networks have contributed to the increasing use of fiber optic networks to meet the increasing demands for data transmission. Optical connector systems have been developed to interconnect optical transmission lines in these networks. One such example of an optical connector is shown in U.S. Pat. No. 5,764,834 to Hultermans. The patent teaches an optical fiber connector having a jack mounted to a motherboard and a plug mounted to a daughterboard. A slidable insert is retained by thrust lances against the shoulder of the plug housing such that the insert can be inserted into a cavity of the jack. Latches of the jack serve to latch onto ribs of the plug insert so as to but a ferrule of the plug against a ferrule of the jack. Insertion of the jack into the plug causes ribs to release the thrust lances of the plug insert such that the insert springs rearward allowing the plug housing to slide forward without spring resistance. A problem exists in that each plug insert contains a ferrule for holding a singular fiber. In order to achieve high-density optical interconnections, multiple fiber ferrules are required. 
     PCT publication WO 98/00741 shows an optical connector system wherein each connector has a ferrule for receiving a plurality of fibers. The ferrule is surrounded by an inner housing and the inner housing is surrounded by an outer housing which is slidable over the inner housing. This arrangement presents an improvement in that a plurality of fibers may be mounted within each ferrule. However, optical interconnection density is limited by the alignment capabilities of a single ferrule and therefore multiple connectors are necessary to achieve high density optical interconnections. It is desirable to increase the optical interconnection density and therefore it is desirable to provide an optical connector having a greater number of interconnections than the present multi fiber ferrule design. 
     SUMMARY 
     It is an object of the present invention to provide an optical interface having precision alignment within a large number of optical interfaces while minimizing the number of components necessary to achieve the interconnection. 
     This and other objects have been achieved by providing an optical interconnection system having a pair of complementary connectors each featuring a plurality of array ferrules that receive a plurality of optical fibers. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1 shows a preferred embodiment of the connector of the present invention along with a mating connector; 
     FIG. 2 shows an exploded view of the connector of FIG. 1; 
     FIG. 3 shows a front view of the connector of FIG. 1; 
     FIG. 4 is a cross-sectional view of the connector of FIG. 1; and 
     FIG. 5 is a cross-sectional view of an alternative embodiment of the connector of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The invention will first be described generally with reference to FIG.  1 . This figure shows an optical connector  2  having an inner housing  12  mounted within an outer housing  14 . The outer housing  14  is slidable over the inner housing  12 . A plurality of ferrules  6  are mounted within the inner housing and at least one cable  35  extends from a rear end  80 . 
     Turning now to FIG. 2 each of the major components will be described in greater detail. Starting at the mating end  10 , the inner housing  12  will now be described in greater detail. The inner housing  12  features a hollow portion  42  extending from a rear end  56  to the mating end  10 . A first ferrule receiving section  50  is disposed between the mating end  10  and hollow portion  42 . Similarly, a second ferrule receiving section  52  is disposed between the mating end  10  and the hollow portion  42 . A latch  46  extends outward toward the mating end  10  adjacent to the second ferrule receiving section  52 . A first shoulder  44  is disposed adjacent the mating end  10  along a top surface  58  of the inner housing  12 . A second shoulder  48  is disposed behind the first shoulder  44  also along the top surface  58 . A projection  53  extends from the top surface  58  behind the second shoulder  48 . A semicircular opening  54  is formed in the top surface  58  and is in communication with the hollow portion  42  near the rear end  56 . 
     The ferrule  6  is profiled to fit within either the first ferrule receiving section  50  or the second ferrule receiving section  52  and features the front portion  62  and a rear portion  72  having larger outer dimensions than the front portion  62 . It should be understood that while a single ferrule  6  is shown here for simplicity, it is preferable to have two such ferrules  6  each positioned in a respective ferrule receiving section  50 ,  52 . A plurality of pin receiving openings  66  extends from the mating face  60  rearward to the rear end  64 . Likewise, a plurality of fiber receiving passageways  68  extends from the mating face  60  to the rear end  64 . A window  70  extends from an outer surface into each of the fiber receiving passageways  68  at a location between the mating face  60  and the rear end  64 . 
     A pin keeper  22  is disposed behind the ferrule  6  and is profiled to have a plurality of slots  16  for receiving pins  8 . It should be understood that while a single pin keeper  22  is shown here for simplicity, it is preferable to have two such pin keepers  22  each positioned behind a respective ferrule  6 . Pins  8  are positioned in the slots  16  of the pin keeper  22  such that they extend toward the mating end  10 . It should be noted here that the pins  8  are optional and are used in one mating connector  2 , 4  or the other. A spring  24  or other suitable biasing device is provided behind the pin keeper  22 . It should be understood that while a single ferrule  6 , pin keeper  22  and spring  24  combination have been shown, the inner housing  12  is designed to receive more than one of each of these components. 
     A crimp plug  29  is disposed behind springs  24  and features a plurality of front portions  74  having cable-receiving passageways  76  extending therethrough. Optionally, the front portions  74  could be formed as a single portion having a plurality of cable-receiving passageways. The cable receiving passageways  76  extend from the front end  26  into a crimp section  27 . The crimp section  27  is profiled to receive a crimp ring  28 . A plurality of securing projections  78  extends from side surfaces of the front portions  74 . The securing projections  78  could optionally be replaced by a single securing projection. 
     The outer housing  14  is a generally hollow component and is open from the rear end  80  to the mating end  10 . A pair of side walls  88  contain side wall openings  92 . The side walls  88  are profiled such that extended portions  91  project outward toward the mating end  10  in the vicinity of a latch receiving opening  90 . A window  86  is provided along an opposite surface and is disposed between a pair of cams  84 . A pair of ledges  82  are disposed along the same surface behind the cams  84 . 
     An optical cable  35  is provided having a plurality of fibers  30  surrounded by an inner jacket  32  and strength members  33  which is surrounded by an outer jacket  34 . A cable boot  18  is slidable over the outer jacket  34 . It should be understood that while a single cable  35  is shown here for simplicity, it is preferable to utilize multiple cables or multiple groups of single fibers in this optical connector  2 . 
     Assembly of the optical connector  2  will now be described in greater detail with reference to FIGS. 2 and 4. First, the cable boot  18 , outer housing  14 , crimp ring  28 , crimp plug  29 , and springs  24  are loaded onto pre-stripped cables  35 . Fibers  30  are then terminated to each of the ferrules  6  using known techniques. For example, the fibers  30  are each inserted into respective fiber receiving passageways  68 , a filler such as a curable epoxy is then flowed through the window  70  to secure fibers  30  within their respective fiber receiving passageways  68 . It should be noted here that the user may optionally load only selected ones of the fiber receiving passageways  68  as required for the particular application. After the epoxy has been cured the fiber ends are then cleaved and polished utilizing known techniques. Pins  8  are assembled into pin keepers  22  by insertion into slots  16 . It should be noted here that the pins  8  are optional and therefore this step may be skipped. The pin keepers  22  are then placed over a respective inner jacket  32  and pins  8  are inserted into pin receiving openings  66  from the rear end  56 . 
     Assembled ferrules  6  and pin keepers  22  are then inserted into respective ferrule receiving sections  50 ,  52  from the rear end  56  of the inner housing  12 . The springs  24  and crimp plug  29  are then inserted into the inner housing  12  from the rear end  56  until securing projections  78  lock into complementary features such as recesses or openings (not shown) on the inside of the inner housing  12 . The outer jacket  34  is pulled over crimp section  27  and the crimp ring  28  is compressed over the outer jacket  34  and strength members  33  to secure it to the crimp section  27 . It should be noted here that the outer jackets  34  have been stripped such that half of their diameters are removed in the vicinity of the crimp section  27 . Therefore, the crimp ring  28  surrounds half of each outer jacket  34 . Outer housing  14  is then assembled over the inner housing  12  and secured thereto by cooperation of projection  53  with the complementary recess inside the outer housing  14 . The recess is preferrably dimensioned to allow the inner housing  12  to slide back and forth within the outer housing  14 . It should noted here as best shown in FIG. 4 that each ferrule  6  is independently biased forward by a spring  24 . 
     An end view the assembled optical connector  2  is shown in FIG.  3 . Two ferrules  6  are mounted inside the inner housing  12 . The fiber receiving passageways  68  are precisely located between the pin receiving openings  66 . Recall that alignment pins  8  may optionally project out of the pin receiving openings  66 . Each fiber receiving passageways contains a fiber  30  having a polished end. 
     Referring now to FIGS. 1 and 4, a mating sequence will be described in greater detail. In an unmated condition as shown in FIG. 4, both ferrules  6  are biased forward against a stop A in the inner housing  12  by the springs  24 . As a pair of optical connectors  2 ,  4  are mated as shown in FIG. 1, alignment pins  8  of the optical connector  2  enter pin receiving openings  66  of the mating connector  4 . The mating faces  6  then engage each other such that the fiber receiving passageway  68  are aligned between the optical connectors  2 , 4 . As the connectors  2 , 4  are further urged toward each other, the ferrules  6  are pressed rearward against the springs  24 . Respective latches  46  engage respective first shoulders  44  to secure the connectors  2  together. 
     An alternate embodiment of an optical connector  102  is shown in FIG.  5 . This optical connector  102  is similar to that of FIGS. 1-4 except that a single alternate spring  124  is utilized instead of two springs  24  for biasing both ferrules  6 . The ferrules  6  are therefore dependently biased and move together. 
     An advantage of the present invention is that a plurality of ferrules  6  can be precisely aligned for an optical interface array within a singular optical connector housing.