Abstract:
An adapter for connecting opposing fiber optic connectors includes a housing having a through aperture about which a post is formed. An alignment sleeve is disposed in and retained by the post. A plastic cap is disposed over an end of the post. The plastic cap may include a lip for retaining the alignment sleeve, a conical or other oblique surface for self-aligning on a like surface of the post, and a latch that clips the cap into recesses in the housing. The post may include a recess for receiving the latch members.

Description:
BACKGROUND 
     The present invention relates to connectors, and more particular to adapters for connecting fiber optic connectors. 
     A conventional fiber optic connector typically includes a body, a plastic ferrule, and a glass fiber disposed concentrically within the ferrule. Each connector may include single or multiple ferrules and fibers. Alignment of opposing fibers upon mating one connector to another is important for proper signal transmission. 
     Adapters for mating a pair of fiber optic connectors often include a housing, a post disposed in the housing, and an alignment sleeve disposed within the post. To shield against electromagnetic interference, among other reasons, the adapter housing is often formed of a conductive or shielding material, and a shielded, hinged cover often covers openings into which fiber optic connectors may be inserted. The alignment sleeve of the adapter receives each of the opposing connectors&#39; ferrules, and often may be formed of a material comprising a ceramic. A longitudinal slot in the alignment sleeves facilitates insertion, retention, and withdrawal of the ferrules. 
     Centering the alignment sleeve relative to the fiber centerline and accurate angular alignment are important to the alignment of the opposing connectors. Misalignment (either angularly and relative to a centerline offset), pinching, or deformation of the alignment sleeve may result in high insertion and withdrawal forces, poor signal transmission, and/or other detriments. 
     The adapter posts typically extend over the ends of alignment sleeve in order to retain it. In such a configuration, contamination of the connector sometimes occurs because of the contact between the dissimilar materials of the ferrule and the post. For example, a plastic ferrule that strikes the front face of a post that is zinc-plated, or the like, during the insertion process may produce particulate that interferes with optical transmission, prevents face-to-face contact of opposing ferrules, and/or other detriments. 
     Further, the connector and adapter industry is competitive such that adapter configuration must be amenable to modern, inexpensive production techniques. 
     SUMMARY 
     An adapter for receiving and connecting together a pair of fiber optic connectors is provided. The adapter comprises a housing including a post supported therein, an alignment sleeve disposed in the post, and a plastic cap disposed proximate an end of the post. The post includes a through-aperture and opposing openings formed therein. The cap includes an opening formed therein, a lip disposed proximate the opening, a contact surface disposed against a mating surface of the post, and a latch including a clip surface in contact with the housing for securing the cap to the post. The lip is disposed over an end of the alignment sleeve to limit longitudinal movement of the alignment sleeve. The cap substantially covers an end of the post such that the ferrule contacts the cap during insertion thereof. Such contact may diminish contamination of the fiber optic connection by the post material. 
     The latch arms fit into notches formed in the posts, and each surface has a draft or wedge shape that prevents the latch arms from moving radially outwardly. Preferably the housing and post are integrally formed of a metallic material that is die cast, and includes frusto-conical ends. The cap preferably includes frusto-conical inboard surfaces that mate to the frusto-conical ends of the posts. Thus, the cap may be self-aligning. 
    
    
     BRIEF DESCRIPTION OF THE FIGURES 
     FIG. 1 is perspective view of an adapter with which the present invention may be employed; 
     FIG. 2 is a perspective cut-away view showing a portion of an embodiment of the adapter according to an aspect of the present invention; 
     FIG. 3 is an enlarged perspective view of a portion of the adapter shown in FIG. 2, 
     FIG. 4 is an enlarged end view of the portion of the adapter shown in FIG. 3; 
     FIG. 5 is an enlarged perspective view of another portion of the adapter that corresponds to the portion shown in FIG. 3; 
     FIG. 6 is an end view of the portion of the adapter shown in FIG. 5; 
     FIG. 7 is an enlarged perspective view of an assembly formed by the portions of the adapter shown in FIG.  3  and FIG. 5; 
     FIG. 8A is a longitudinal cross-sectional view of the portion of the adapter shown in FIG. 3; 
     FIG. 8B is a longitudinal cross-sectional view of the portion of the assembly shown in FIG. 7; and 
     FIG. 9 is an exploded, perspective view of the adapter shown in FIG.  1 . 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     An adapter  10  according to an aspect of the present invention includes a housing  12 , a post  14 , at least one plastic cap, such as caps  16   a  and  16   b , and an alignment sleeve  18 . A duplex adapter is employed to illustrate aspects of the present invention, although the present invention is not limited to any particular quantity of adapter apparatus. Referring to the Figures to illustrate an embodiment of the present invention, FIG. 1 shows an exterior view of a housing  12 . Housing  12  includes a through-opening  20 , which is best shown in FIG.  2 . 
     As best shown in FIGS. 2 through 4 and  7 , housing  12  includes a bulkhead  22  that partially interrupts through-opening  20  and that supports post  14 . Preferably, housing  12 , post  14 , and bulkhead  22  are integrally formed by die casting of a metallic or electro-magnetic shielding material. Conventional die casting techniques may be employed to integrally cast components  12 ,  14 , and  22  according to conventional industry tolerances. The present invention is not limited to forming post  14  integrally with housing  12 , but rather also encompasses any assembly techniques. Further, the present invention is not limited to any particular materials or manufacturing techniques. 
     The post  14  includes opposing first and second post portions  24   a  and  24   b  that extend outwardly from bulkhead  22 . The post portions  24   a  and  24   b  are illustrated as substantially identical or mirror images, although the present invention is not limited to such a configuration. For convenience of illustration, the features of each post  24   a  and  24   b  will be referred to herein by reference numerals without appended letter designation, and a letter designation will be appended to a particular feature when referring to the feature of a particular one of posts  24   a  and  24   b  where beneficial to the understanding of the description. Each one of posts  24   a  and  24   b  includes a substantially cylindrical portion  28 . Preferably, the distal end of cylindrical portion  28  includes a surface that is oblique, in transverse cross section, relative to longitudinal centerline L. For example, as shown in the Figures, the distal end of each cylindrical portion  28  is formed substantially in the shape of a frustum  30  of a right circular cone. 
     Cylindrical portion  28  and the frusto-conical portion  30  are provided with notches  34  formed therein. As best shown in FIG.  2  and FIG. 7, notches  34  preferably are formed in opposing sides of post  24   a . Each of notches  34  includes an inboard portion  36 ′ and an outboard portion  36 ″. Preferably, inboard portion  36 ′ has a width, in transverse cross section, that is larger than the width of outboard portion  36 ″, thereby forming a draft slot or a key slot. 
     Again employing letters appended to the reference numerals to refer to particular structure corresponding to the first and second posts  24   a  and  24   b , a pair of first recesses or windows  26   a  is formed in bulkhead  22  on opposing sides of first post  24   a . Similarly, a pair of second recesses or windows  26   b  is formed in bulkhead  22  on opposing sides of second post  24   b . Preferably, first windows  26   a  are spaced approximately 180 degrees apart and are in line with notches  34   a  of first post  24   a . Likewise, second windows  26   b  are spaced approximately 180 degrees apart and are in line with notches  34   b  of second post  24   b . First windows  26   a  are spaced apart from second windows  26   b  by approximately 90 degrees such that first windows  26   a  are equidistant from second windows  26   b.    
     Referring to FIGS. 5 through 8A and  8 B, and again only employing a letter designation to refer to a particular one of caps  16   a  and  16   b , cap  16  includes a ring  40  in which an aperture  42  is formed. Ring  40  forms a front face  41  on an outboard side thereof, and a contact surface  44  on an underside thereof. Contact surface  44  includes a surface that is oblique, in transverse cross section, relative to longitudinal centerline L. For example, as shown in the Figures, contact surface  44  forms a frustum of a right circular cone that substantially matches the configuration of post frusto-conical portion  30 . A lip  46  is formed on contact surface  44  and protrudes radially inwardly relative to aperture  42 . 
     A pair of opposing latch arms  48  extend from ring  40 , and include a longitudinally oriented portion  52  and a latch means, such as latch  54 , disposed proximate a distal end of longitudinal member  52 . Member  52  preferably has, in transverse cross section, a draft or key shape that substantially matches the cross-sectional shape of notch  34 . Latch  54  is capable of radial, spring-like movement. For example, longitudinal member  52 , which preferably is cantilevered from ring  40 , is flexible to enable the spring-like movement of latch  54 . Latch  54  includes a clip surface  56  disposed thereon. 
     As best shown in FIG. 8B, the radially inboard side of the longitudinal portion  52  may include a taper  53 , which facilitates the inward deflection of the distal end of latch  54  during insertion of cap  16   a  and  16   b  through windows  26   a  and  26   b , as explained more fully below. 
     Alignment sleeve  18  is disposed within posts  24   a  and  24   b  and longitudinally restrained by lips  46   a  and  46   b . Alignment sleeve  18 , which may be formed of a ceramic or other suitable material as understood by persons familiar with adapter technology and materials, preferably is cylindrical and includes a longitudinal slot  60  (FIG. 7) formed therein. 
     To assembly caps  16   a  and  16   b  and alignment sleeve  18  with posts  24   a  and  24   b , alignment sleeve  18  may be inserted through one of the post openings  32   a  or  32   b . The internal diameter of posts  24   a  and  24   b  are sufficiently large to receive alignment sleeve  18  according to conventional manufacturing considerations. Caps  16   a  and  16   b  may be aligned such that longitudinal members  52  are aligned with notches  34 . As caps  16   a  and  16   b  are applied to posts  24   a  and  24   b , respectively, longitudinal members  52  slide into notches  34  until a distal tip of latch  54  extends through windows  26   a  and  26   b . A tapered portion  58  (FIG. 5) of the out board side of the distal tip of latch  54  strikes a corresponding tapered portion or ramp  59  (FIG. 3) formed proximate bulkhead  22  on a radially outboard side of windows  26 . 
     The draft surfaces of notches  34  and longitudinal members  52  are oriented to enable members  52  to flex or deflect radially inwardly and restrain radial outward deflection of latch arms  48 . The tapered surfaces  58  and  59  are oriented to urge latch  54  radially inwardly upon contact therebetween (that is, near the full-insertion position of caps  16   a  and  16   b ). Thus, latch arms  48  flex radially inwardly in response to urging of latch tapered surface  58  against housing tapered surface  59 , thereby enabling latch  54  to move past housing tapered surface  59 . Latch contact surface  56  seats onto a corresponding contact surface  57  (FIG. 8B) of housing  12 . 
     The draft surfaces of notches  34  and longitudinal members  52  restrain latch arms  48  from moving radially outwardly while caps  16   a  and  16   b  are latched, which facilitates coupling with a connector, such as a conventional LC connector. In this regard, posts  24   a  and  24   b  are insertable into the annulus of such a conventional connector, such as an LC connector, between its housing and ferrule without interference by the latch arms  48  of caps  16   a  and  16   b.    
     Preferably, lips  46   a  and  46   b  lightly touch alignment sleeve  18  or form a slight gap therebetween to enable alignment sleeve to self-align, if necessary, upon insertion of a connector from either end thereof. The present invention also encompasses lips  46   a  and  46   b  tightly contacting sleeve  18  to secure sleeve  18  therebetween in a press fit. Integrally forming post  14  with housing  22  facilitates alignment of sleeve  18  by, for example, eliminating any pinching or misalignment that may be formed between non-integrally formed posts. 
     Face  41  of caps  16   a  and  16   b  provides a plastic surface against which the plastic ferrule of the connector may strike upon insertion of the connector into adapter  10  until the ferrule locates cap aperture  42 . Because a plastic surface (that is, of the ferrule) strikes another plastic surface (that is, of cap  16 ), as distinguished from a metallic or metallic coated surface, metal contamination of the interface between opposing optical fibers and metal interference between the abutting faces of the opposing ferrules of the connectors is eliminated or diminished. 
     Referring again to FIG.  1  and FIG. 9, adapter  10  includes a pair of shutter doors  70  that are coupled to housing  12  by a pin  76 . Housing  12  includes a pair of outer housing lugs  74  that are insertable into a pair of door lugs  72 . A center housing lug  75  is disposed on the housing between outer housing lugs  74 . A torsion spring  78  is disposed between each one of the outer housing lugs  74  and the inner housing lug  75 . Apertures of lugs  72 ,  74 , and  75  and of springs  78  are aligned to enable pin  76  to be disposed therethrough. Pin  76  is held in place by kink that is formed by deforming a portion of pin  76 . For example, as shown in FIG. 1, center housing lug  75  is provided with an aperture for accessing pin  76 . A punch tool (not shown in the Figures, but which may be any pointed object of proper size) may be inserted into the aperture in center lug  75  to form the kink in pin  76 . 
     The present disclosure illustrates the invention by describing a particular embodiment and referring to some advantages. The present invention, however, is not limited to such an embodiment, but rather encompasses any adapter, connector, and the like that incorporates the present invention, as recited in the appended claims. For example, a duplex adapter is shown, and the present invention encompasses any type of single or multiple device. Further, the present invention is not limited to employing a bulkhead, but rather encompasses any means to support a post or like structure. The post, or like structure, need not by cylindrical, but rather may be square or rectangular, oval or elliptical, or any combination of straight and curved portions in transverse cross section. Other variations will be apparent to persons familiar with connector and adapter technology in view of the present disclosure, and such variations are encompassed by the present invention, as provided in the appended claims.