Coupling for optical-fiber connectors

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.

The invention relates to a coupling for accommodating plug-in connectors according to the preamble of patent claim1.

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.

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.

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.

The problem is solved by the subject matter having the features of claim1. Further advantageous configurations of the invention can be gathered from the subclaims.

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.

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.

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.

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.

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.

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.

In one development, the connection piece is formed integrally with the covering. This development is distinguished by particular stability.

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.

In a further embodiment, the connection piece is designed, for secure attachment, with centering pins.

FIG. 1shows, schematically, a coupling1for the coaxial connection of fiber-optic cables. The coupling comprises a coupling housing10into which a plug-in connector2can be plugged in from each end. The coupling housing10is designed with flanges106, by means of which the coupling1can be attached to an installation opening (not illustrated). A connection piece13can be latched onto the coupling housing10. The length of the connection piece13may be selected here such that there is no blockage of access to the grip region22provided on the plug-in connector2in the plugged-in state. The plug-in connector2is designed, for assisting guidance in the coupling housing10, with a tongue21, which can be introduced into a complementary groove101on the coupling housing10and into a groove131on the connection piece13.

FIG. 2shows a section through the coupling1and the plug-in connector2. The designations here correspond toFIG. 1. A sleeve mount11with a sleeve12is mounted in the coupling housing10. The plug-in connector2is designed with a ferrule23at its free end. Two plug-in connectors2which are to be connected come into contact in the sleeve12via the end surfaces of the ferrules23, with the result that light waves can be transmitted via the fiber-optic cables formed with the plug-in connectors2. With a plug-in connector2plugged in on one side, the emission of light waves from a sleeve opening121has to be prevented. For this purpose, the sleeve opening121can be covered via a leaf spring141. The leaf spring141may be selected to be very thin, with the result that, with the plug-in connector2placed in position, said spring is in close abutment in a depression of the housing wall and does not obstruct the plug-in connector2from being accommodated.

FIG. 3shows a perspective illustration of the coupling1. The designations here correspond toFIGS. 1 and 2. The connection piece13can be latched onto the coupling housing10. For the latching fastening, the connection piece13is designed with latching tongues134, which have through-passages135. The coupling housing10is designed, on the contact surfaces104of the latching fastening, with latching noses105, which latch into the through-passages135. The connection piece13does not change the width and depth of the coupling1, 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 piece13to be designed with latching noses and the coupling housing10to be designed with through-passages.

FIG. 4shows the connection piece13schematically. The designations here correspond toFIGS. 1 to 3. The connection piece13may be attached to the coupling housing10(not illustrated) by means of centering pins132, which engage in complementary bores102(seeFIG. 3) in the coupling housing10. The through-passages135and the complementary latching noses105are offset vertically in relation to one another. This makes it possible for the latching noses105to be formed straightforwardly in the coupling housing10, which is illustrated inFIG. 1. However, other shapes and arrangements of the latching noses105are conceivable. It is also conceivable for the latching tongues134, rather than extending over the entire width of the connection piece13, only to cover a region around the latching noses105in each case. Additional latching fastenings on the two remaining side surfaces are likewise conceivable. However, an additional latching fastening must not conceal the groove131, which is provided for orienting and/or positioning the plug-in connectors2, or obstruct the movement of the leaf spring141, which is provided tangentially to the side surface136. The latching fastening illustrated, comprising two latching tongues on mutually opposite housing walls, is thus particularly advantageous.

FIG. 5shows a covering14designed with leaf spring141and wings142. The covering14is attached to the coupling1by means of the wings142. The size of the wings142here is limited by the outer dimensions of the coupling1. In principle, however, it is also possible for the leaf spring141to be attached directly via a tangential extension of the leaf spring.

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 spring141is not subjected to loading and covers the sleeve opening121. The leaf spring141is designed with a curvature which, at one end, runs tangentially to the side surface136. The ferrule23of the plug-in connector2is 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 ferrule23must not come into contact with the leaf spring141during the plug-in process. The curvature of the leaf spring141thus has to be adapted in accordance with the geometry of the plug-in connector2.FIG. 6(b) shows the displacement of the leaf spring141by a relatively wide termination surface24of the plug-in connector2. A sufficient spacing between the ferrule2and the leaf spring141is ensured here. Laser-beam emission from the coupling housing10in the axial direction on account of the sleeve opening121being released is prevented by the plug-in connector2.FIG. 6(c) shows the end of the plug-in operation. The plug-in connector2is accommodated in the coupling1by latching means. The leaf spring141here has been displaced into the depression of the housing wall by the plug-in connector2. The very thin configuration of the leaf spring141causes it to fit very snugly into the depression of the housing wall. Fitting the cover14for protection against the emission of laser radiation thus does not require either plug-in connectors2provided to be changed or the size of the coupling housing10to be increased.

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 sleeve12. For additional dust protection when the plug-in connector2is subjected to pulling, use has to be made, for example, of a dust-protection cap3illustrated inFIG. 7. The dust-protection cap3is designed with a cylinder31by means of which the cap can be accommodated by the sleeve mount11, illustrated inFIG. 2for example, of the coupling1. In the case of such a dust-protection configuration, the sleeve12is sealed precisely at the critical location. The diameter of the cylinder31is only dependent on the geometry of the sleeve mount11, and is thus not dependent on the use of the connection piece13. The dust-protection cap3can be aligned by a tongue32. The tongue32here engages in the groove101, illustrated inFIG. 1, of a coupling housing10and, if a connection piece13is used, also in the groove131. The length of the tongue32here does not have to correspond either to the length of the groove101or of the grooves101and131, 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 housing10and/or of the connection piece13. 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 groove101or the grooves101and131has/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 coupling1, illustrated inFIG. 1, with or without a connection piece13. That end of the dust protector3which is directed away from the coupling1is designed with a fixing means33. Via the fixing means33, the withdrawn dust-protection cap3can be fastened on a cable of a plug-in connector accommodated by the coupling1. The fixing means33comprises a pivotable cover331, which is designed with a latching hook334, and a groove333, which complements the latching hook334. The latching hook334here may be designed such that different latching positions may be assumed when the cover331is closed. The fiber-optic cable can be positioned in one of the bores335when the cover331has been swung open. The bores335have different radii, with the result that the dust-protection cap3can be fixed on cables with a wide range of different diameters. The outwardly oriented surface332of the cover331here provides a good inscription surface, which is easily accessible when the coupling1is attached to a front panel.

FIG. 8shows a second embodiment of a fixing means33on the dust-protection cap3. The designations here correspond toFIG. 7. In the second embodiment, the fixing means33is designed with a latching connection34into which the fiber-optic cable can be latched. The latching connection34has bores341of different diameters, with the result that they can be plugged onto a multiplicity of different cable diameters. Also conceivable instead of the bores341are sawtooth-like formations, by means of which different cables can be fixed and/or clamped in. If the plug-in direction of the latching connection34coincides with the axis of the cylinder41, 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 connection34, with a plug-in direction perpendicular to the axis of the cylinder31, which is illustrated inFIG. 8is thus advantageous. This second embodiment of the fixing means33can be produced in one piece, and thus cost-effectively. The straightforward latching onto a cable is also advantageous. Further embodiments of the fixing means33, 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.

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