Abstract:
A coupling ( 1 ) for receiving at least two plug-in connectors ( 2 ) which are joined to glass fiber cables, comprising at least one moveable cover ( 14 ) which is associated with a sheath opening ( 121 ), said cover covering the opening ( 121 ) of the sheath in a first position, and being able to be moved into a second position by introducing a plug-in connector ( 2 ), whereupon the cover ( 14 ) releases the opening ( 121 ) in the sheath, said cover ( 14 ) comprising a bent metallic leaf spring ( 141 ) and said leaf spring ( 141 ) being unstressed in the first position and the curvature of the leaf spring ( 141 ) being selected in such a way that a ferrule ( 23 ) of the plug-in connector ( 2 ) never comes into contact with the leaf spring ( 141 ) during the insertion process.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a Continuation of application Ser. No. 10/513,243, filed 1 Sep. 2005, which is the National Stage of Application PCT/EP03/04293, filed 25 Apr. 2003, which claims benefit to 102 19 892.6, filed 3 May 2002 in Germany, and which applications are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    It is known for optical fibers to be connected coaxially to plug-in connectors by means of couplings. The plug-in connectors are designed with a ferrule at the free end for the purpose of central fixing. The two ferules of the plugs which are to be connected can be introduced into a sleeve of the corresponding coupling, the ferrules coming into contact at the end surfaces. The sleeve is mounted in a sleeve mount. The outer shape of the coupling housing is defined by way of the given geometries of a known installation opening. Light waves are transmitted by fiber-optic cables. In order to prevent the emission of harmful laser radiation when the plug is subjected to pulling on one side, a protective device is necessary. 
         [0003]    A coupling with a protective device is known, for example, from EP 0 599 784 A1, there being arranged in front of the sleeve opening, as seen in the plug-in direction, a moveable protective flap which, in a closed position, at least partially overlaps the sleeve opening and, in order for the contact pin to be plugged in, can be moved into an open position, the device having an inner bushing housing which can be pushed into an outer bushing housing, and the protective flap being retained, and mounted pivotably, between the two bushing housings. The disadvantage with such a protective device is the amount of space taken up by the pivoting mechanism, with the result that it cannot be realized with small outer dimensions of the coupling. In addition, the high-outlay mechanism is cost-intensive to produce. 
       SUMMARY OF THE INVENTION 
       [0004]    The invention is thus based on the technical problem of providing a coupling which is intended for accommodating plug-in connectors connected to fiber-optic cables and which, with small outer dimensions of the coupling, provides protection against the emission of harmful laser radiation and can be produced cost-effectively. 
         [0005]    The emission of harmful laser radiation from a sleeve opening of a plug receptacle can be prevented by a covering assigned to the same, the covering comprising a bent metallic leaf spring which, in a first, non-loaded position, covers the sleeve opening and, by the introduction of a plug into the plug receptacle, can be moved into a second position, the sleeve opening being free in the second position, and the bending of the leaf spring being selected such that the ferrule does not come into contact with the leaf spring at any point in time during the plug-in operation. The leaf spring is to be selected here such that there is no need for any unnecessary application of force for the plug-in operation, and pronounced loading of the plug on account of the force of the leaf spring in the plugged-in state is avoided. At the same time, the elasticity of the leaf spring ensures that, when the plug is subjected to pulling, reliable return into the non-loaded position takes place. A metallic covering of the sleeve opening is distinguished by good thermal stability. Moreover, the metallic leaf spring allows a very thin configuration of the covering, although the sleeve opening is shielded to good effect. Even colored plastic flaps for covering the sleeve opening require a considerably thicker configuration. In order, in this case, not to obstruct the plug from being accommodated by the covering, a change in the outer shape of the coupling housing is necessary. Changes in the outer shape, however, are undesirable for the purpose of ensuring compatibility with the standard or that further couplings can be added on in a compact manner. 
         [0006]    In a preferred embodiment, the covering is formed integrally with a leaf spring and two wings. Via the wings, the covering can be attached tangentially to a housing wall, the movement of the leaf spring being disrupted as little as possible by this attachment. The wings here are limited by the maximum outer dimensions of the coupling. 
         [0007]    In one development, the means for accommodating the covering is designed as a separate connection piece which can be connected to the coupling housing. This makes it possible for the connection piece and the coupling housing to be produced separately. This is advantageous since, for example, the material can be selected in accordance with the respective requirements. It is also conceivable for couplings to be used in situations where they do not require any protective device against the emission of laser light. A two-part configuration of the protective device and of the coupling housing allows specific use of the protective device. A single-piece embodiment, however, is more stable and may thus be necessary for specific applications. 
         [0008]    In one embodiment, the covering is fastened tangentially to the housing wall by hot stamping. The hot-stamping attachment can be realized cost-effectively. In addition, it is possible to produce the attachment both in the case of a single-piece configuration and in the case of a two-part configuration of the coupling housing and of the connection piece from plastic. 
         [0009]    In a preferred embodiment, the connection piece is designed as a plastic part, it being possible for the covering to be connected to the connection piece by injection-molding encapsulation. This makes it possible to realize very good attachment of the covering to the connection piece. 
         [0010]    In a further embodiment, the connection piece is designed as a separate sheet-metal part, the covering, configured as a leaf spring, being integrated in the sheet-metal part. Various methods such as spot welding or adhesive bonding are conceivable for attaching the leaf spring to the connection piece. The configuration of the connection piece as a sheet-metal part provides a higher stability than a plastic configuration. 
         [0011]    In one development, the connection piece is formed integrally with the covering. This development is distinguished by particular stability. 
         [0012]    In a preferred embodiment, the connection piece is attached to the coupling housing by a latching fastening. A latching fastening is advantageous since, on the one hand, automated installation can easily be realized but, on the other hand, it is also possible to provide a releasable connection. This makes it possible for the couplings to be adapted specifically to the respective use. 
         [0013]    In a further embodiment, the connection piece is designed, for secure attachment, with centering pins. 
         [0014]    The invention is explained in more detail hereinbelow with reference to a preferred exemplary embodiment. In the figures, schematically in each case: 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  shows a plan view of a coupling for coaxial optical-fiber connection and of a plug-in connector, 
           [0016]      FIG. 2  shows a section through the plan view shown in  FIG. 1 , 
           [0017]      FIG. 3  shows a perspective illustration of a coupling housing and of a connection piece, 
           [0018]      FIG. 4  shows a perspective illustration of the connection piece, 
           [0019]      FIG. 5  shows a perspective illustration of a covering, 
           [0020]      FIGS. 6  ( a )-( c ) show sectional illustrations of the coupling and of the plug-in connector during the plug-in operation, 
           [0021]      FIG. 7  shows a perspective illustration of a first embodiment of a dust-protection cap, and 
           [0022]      FIG. 8  shows a perspective illustration of a second embodiment of the dust-protection cap. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0023]      FIG. 1  shows, schematically, a coupling  1  for the coaxial connection of fiber-optic cables. The coupling comprises a coupling housing  10  into which a plug-in connector  2  can be plugged in from each end. The coupling housing  10  is designed with flanges  106 , by means of which the coupling  1  can be attached to an installation opening (not illustrated). A connection piece  13  can be latched onto the coupling housing  10 . The length of the connection piece  13  may be selected here such that there is no blockage of access to the grip region  22  provided on the plug-in connector  2  in the plugged-in state. The plug-in connector  2  is designed, for assisting guidance in the coupling housing  10 , with a tongue  21 , which can be introduced into a complementary groove  101  on the coupling housing  10  and into a groove  131  on the connection piece  13 . 
         [0024]      FIG. 2  shows a section through the coupling  1  and the plug-in connector  2 . The designations here correspond to  FIG. 1 . A sleeve mount  11  with a sleeve  12  is mounted in the coupling housing  10 . The plug-in connector  2  is designed with a ferrule  23  at its free end. Two plug-in connectors  2  which are to be connected come into contact in the sleeve  12  via the end surfaces of the ferrules  23 , with the result that light waves can be transmitted via the fiber-optic cables formed with the plug-in connectors  2 . With a plug-in connector  2  plugged in on one side, the emission of light waves from a sleeve opening  121  has to be prevented. For this purpose, the sleeve opening  121  can be covered via a leaf spring  141 . The leaf spring  141  may be selected to be very thin, with the result that, with the plug-in connector  2  placed in position, said spring is in close abutment in a depression of the housing wall and does not obstruct the plug-in connector  2  from being accommodated. 
         [0025]      FIG. 3  shows a perspective illustration of the coupling  1 . The designations here correspond to  FIGS. 1 and 2 . The connection piece  13  can be latched onto the coupling housing  10 . For the latching fastening, the connection piece  13  is designed with latching tongues  134 , which have through-passages  135 . The coupling housing  10  is designed, on the contact surfaces  104  of the latching fastening, with latching noses  105 , which latch into the through-passages  135 . The connection piece  13  does not change the width and depth of the coupling  1 , with the result that the tasks of attaching the coupling to a front panel (not illustrated) and of adding on further couplings are not adversely affected. It is also possible, in principle, for the connection piece  13  to be designed with latching noses and the coupling housing  10  to be designed with through-passages. 
         [0026]      FIG. 4  shows the connection piece  13  schematically. The designations here correspond to  FIGS. 1 to 3 . The connection piece  13  may be attached to the coupling housing  10  (not illustrated) by means of centering pins  132 , which engage in complementary bores  102  (see  FIG. 3 ) in the coupling housing  10 . The through-passages  135  and the complementary latching noses  105  are offset vertically in relation to one another. This makes it possible for the latching noses  105  to be formed straightforwardly in the coupling housing  10 , which is illustrated in  FIG. 1 . However, other shapes and arrangements of the latching noses  105  are conceivable. It is also conceivable for the latching tongues  134 , rather than extending over the entire width of the connection piece  13 , only to cover a region around the latching noses  105  in each case. Additional latching fastenings on the two remaining side surfaces are likewise conceivable. However, an additional latching fastening must not conceal the groove  131 , which is provided for orienting and/or positioning the plug-in connectors  2 , or obstruct the movement of the leaf spring  141 , which is provided tangentially to the side surface  136 . The latching fastening illustrated, comprising two latching tongues on mutually opposite housing walls, is thus particularly advantageous. 
         [0027]      FIG. 5  shows a covering  14  designed with leaf spring  141  and wings  142 . The covering  14  is attached to the coupling  1  by means of the wings  142 . The size of the wings  142  here is limited by the outer dimensions of the coupling  1 . In principle, however, it is also possible for the leaf spring  141  to be attached directly via a tangential extension of the leaf spring. 
         [0028]      FIGS. 6  ( a )-( c ) show, schematically, different points in time during a plug-in process.  FIG. 6  ( a ) shows the beginning of the plug-in process. At this point in time, the leaf spring  141  is not subjected to loading and covers the sleeve opening  121 . The leaf spring  141  is designed with a curvature which, at one end, runs tangentially to the side surface  136 . The ferrule  23  of the plug-in connector  2  is worked in a highly precise manner and is thus very sensitive. For this reason and due to a risk of contamination, for example, by metal abrasion, the ferrule  23  must not come into contact with the leaf spring  141  during the plug-in process. The curvature of the leaf spring  141  thus has to be adapted in accordance with the geometry of the plug-in connector  2 .  FIG. 6  ( b ) shows the displacement of the leaf spring  141  by a relatively wide termination surface  24  of the plug-in connector  2 . A sufficient spacing between the ferrule  2  and the leaf spring  141  is ensured here. Laser-beam emission from the coupling housing  10  in the axial direction on account of the sleeve opening  121  being released is prevented by the plug-in connector  2 .  FIG. 6  ( c ) shows the end of the plug-in operation. The plug-in connector  2  is accommodated in the coupling  1  by latching means. The leaf spring  141  here has been displaced into the depression of the housing wall by the plug-in connector  2 . The very thin configuration of the leaf spring  141  causes it to fit very snugly into the depression of the housing wall. Fitting the cover  14  for protection against the emission of laser radiation thus does not require either plug-in connectors  2  provided to be changed or the size of the coupling housing  10  to be increased. 
         [0029]    The protective device described only provides protection against the emission of harmful laser radiation. In most cases, this device does not provide sufficient protection against the penetration of dust and other contaminants into the sleeve  12 . For additional dust protection when the plug-in connector  2  is subjected to pulling, use has to be made, for example, of a dust-protection cap  3  illustrated in  FIG. 7 . The dust-protection cap  3  is designed with a cylinder  31  by means of which the cap can be accommodated by the sleeve mount  11 , illustrated in  FIG. 2  for example, of the coupling  1 . In the case of such a dust-protection configuration, the sleeve  12  is sealed precisely at the critical location. The diameter of the cylinder  31  is only dependent on the geometry of the sleeve mount  11 , and is thus not dependent on the use of the connection piece  13 . The dust-protection cap  3  can be aligned by a tongue  32 . The tongue  32  here engages in the groove  101 , illustrated in  FIG. 1 , of a coupling housing  10  and, if a connection piece  13  is used, also in the groove  131 . The length of the tongue  32  here does not have to correspond either to the length of the groove  101  or of the grooves  101  and  131 , since no sealing is required there. In addition, it is also conceivable to provide dust protection by a cap which seals over the end sides of the coupling housing  10  and/or of the connection piece  13 . The advantage with sealing over the end sides is that the entire coupling interior is protected. In order to ensure that the interior is sealed, the groove  101  or the grooves  101  and  131  has/have to be closed by corresponding tongues on the cap. The configuration of the cap is thus no longer dependent on the configuration of the coupling  1 , illustrated in  FIG. 1 , with or without a connection piece  13 . That end of the dust protector  3  which is directed away from the coupling  1  is designed with a fixing means  33 . Via the fixing means  33 , the withdrawn dust-protection cap  3  can be fastened on a cable of a plug-in connector accommodated by the coupling  1 . The fixing means  33  comprises a pivotable cover  331 , which is designed with a latching hook  334 , and a groove  333 , which complements the latching hook  334 . The latching hook  334  here may be designed such that different latching positions may be assumed when the cover  331  is closed. The fiber-optic cable can be positioned in one of the bores  335  when the cover  331  has been swung open. The bores  335  have different radii, with the result that the dust-protection cap  3  can be fixed on cables with a wide range of different diameters. The outwardly oriented surface  332  of the cover  331  here provides a good inscription surface, which is easily accessible when the coupling  1  is attached to a front panel. 
         [0030]      FIG. 8  shows a second embodiment of a fixing means  33  on the dust-protection cap  3 . The designations here correspond to  FIG. 7 . In the second embodiment, the fixing means  33  is designed with a latching connection  34  into which the fiber-optic cable can be latched. The latching connection  34  has bores  341  of different diameters, with the result that they can be plugged onto a multiplicity of different cable diameters. Also conceivable instead of the bores  341  are sawtooth-like formations, by means of which different cables can be fixed and/or clamped in. If the plug-in direction of the latching connection  34  coincides with the axis of the cylinder  41 , a possible inscription surface is dispensed with. However, fixing means which allow the inscription surface to be maintained are to be used in preference. The design of the latching connection  34 , with a plug-in direction perpendicular to the axis of the cylinder  31 , which is illustrated in  FIG. 8  is thus advantageous. This second embodiment of the fixing means  33  can be produced in one piece, and thus cost-effectively. The straightforward latching onto a cable is also advantageous. Further embodiments of the fixing means  33 , for example fixing on the coupling housing by a chain or a flexible strap or by latching or plugging onto the coupling housing, are likewise conceivable. 
         [0031]    Designing the coupling with a protective device according to the invention and with a dust protector means that, when the plug is subjected to pulling, the coupling is protected against the penetration of contaminants and the environment is protected against the emission of laser radiation. The protective device and the dust protector, however, are not mutually dependent. 
       LIST OF DESIGNATIONS 
       [0000]    
       
         
           
               1  Coupling 
               10  Coupling housing 
               101  Groove 
               102  Bore 
               104  Contact surface 
               105  Latching nose 
               106  Flange 
               11  Sleeve mount 
               12  Sleeve 
               121  Sleeve opening 
               13  Connection piece 
               131  Groove 
               132  Centering pin 
               134  Latching tongue 
               135  Though-passage 
               136  Side surface 
               14  Covering 
               141  Leaf spring 
               142  Wing 
               2  Plug-in connector 
               21  Tongue 
               22  Grip region 
               23  Ferrule 
               24  Termination surface 
               3  Dust-protection cap 
               31  Cylinder 
               32  Tongue 
               33  Fixing means 
               331  Cover 
               332  Inscription surface 
               333  Groove 
               334  Latching hook 
               335  Bore 
               34  Latching connection 
               341  Bore