Abstract:
The invention relates to an optical connector for connecting optical fibers. Said connector comprises a housing which is provided with a first opening for an optical cable comprising an optical fiber to be connected, and a second opening, through which the end of the optical fiber outwardly protrudes from the housing. The second opening can be closed by a lid which can be pivoted between a first position in which it closes the second opening, and a second position in which it frees the second opening. Spring elements are provided for prestressing the lid in the closing direction. The aim of the invention is to simplify the structure and especially the assembly of one such connector. To this end, the spring elements comprise a laminated spring.

Description:
BACKGROUND OF THE INVENTION 
   Field of the Invention 
   The present invention relates to the field of optical plug-in connections. 
   Description of Related Art 
   In fiber-optic communications technology, use has long been made of optical connector systems in which two optical fibers are coupled to each other by two connectors, in each of which one of the fibers ends in a ferrule, being inserted from opposite sides into a coupling or an adapter in such a way that the ferrules slide from both sides into a guiding sleeve arranged in the coupling and butt with the end faces against each other. Connector systems of this type are known and marketed under the designation SC, LC, E2000,LSH or LX.5. 
   In some of the known connector systems, the connectors are equipped with pivotable protective covers, which in the non-inserted state of the connector cover the opening from which the ferrule protrudes with the end of the fiber and so on the one hand protect the sensitive coupling-in surface of the optical fiber from being soiled or damaged and on the other hand prevent laser radiation that is guided in the optical fiber from penetrating to the outside and possibly causing personal injury. Optical connectors of this type that are provided with pivotable protective covers are disclosed for example in EP-B1-0 570 652, E-A1-0 823 649,EP-A1-1 072 917, U.S. Pat. No. 5,883,995 or the initially cited U.S. Pat. No. 6,142,676. 
   In principle, it is possible to actuate, or swing open and closed, the pivotable covers on the connectors without the aid of spring elements exclusively by the interaction of actuating elements arranged on the cover and in the coupling. Such spring-less solutions are described in U.S. Pat. No. 5,883,995 and in EP-B1-0 570 652. 
   In order to ensure that the covers are reliably closed and kept closed, however, spring elements which prestress the cover in the closing direction and consequently both bring about automatic closing and provide a resistance to counter opening of the cover, and so significantly reduce the risk of unintentional swinging open, are increasingly being used on the connectors. 
   In EP-A1-0 823 649, a cover which performs a combined pivoting and sliding movement is provided on the connector; during opening, it is initially swung open and then pushed linearly to the rear in the direction of the connector axis. In order to prestress the cover in the closing direction, a spiral spring which lies parallel to the connector axis and acts via a push rod (11 in  FIG. 2 ) on a lever arm (12 in  FIG. 2 ) formed onto the cover is provided in this case. A comparable mechanism is also shown in EP-A1-1 072 917.In both cases, the closed position of the cover is the only stable position. In any other position of the cover, the pressure of the spring always acts in the direction of this closed position. 
   Another situation is obtained with the solution of the initially cited U.S. Pat. No. 6,142,676 ( FIG. 33  et seq). Although a spiral spring for acting on the cover is likewise provided here, the spiral spring is fastened with one end to the cover and seated with the other end on a pivotably mounted pin. At the same time, the cover performs a straightforward pivoting movement. This results in a kind of snap mechanism in which the cover can optionally assume two stable positions, that is the completely opened position and the completely closed position: if the cover is swung up out of the closed position, the spiral spring is increasingly compressed, until it is compressed to the maximum extent in a predetermined intermediate position of the cover. If the cover swings beyond the predetermined intermediate position, the spiral spring expands again. As a consequence of this, the cover is pressed by the spiral spring either into the opened position or into the closed position, depending on on which side of the predetermined intermediate position it is located at the time. The additional prestressing of the cover in the opened position has in this case the advantage in particular that the cover is optimally positioned during pulling out from the coupling for the subsequent closing movement. 
   Problems when spiral springs are used for prestressing the protective covers in the closing direction arise in particular because the spiral springs are difficult to handle during assembly and in particular cause problems in automated assembly. These problems become all the greater the smaller the connectors become. This applies in particular to the so-called SFF (Small Form Factor) connectors, as are described for example in the initially cited U.S. Pat. No. 6,142,676. 
   SUMMARY OF THE INVENTION 
   The object of the invention is to provide an optical connector on which the pivotable protective cover is prestressed in the closing direction by spring means and which can be assembled without difficulty, and in particular also automatically, even with further reduced dimensions. 
   The object is achieved by the features of claim  1  in their entirety. The essence of the invention is to use for the prestressing of the cover a leaf spring which, on account of its simple geometry and mode of operation, can be attached particularly easily to the connector and which is also suitable for equipping the cover with a bistable pivoting mechanism. 
   A first preferred configuration of the invention is distinguished by the fact that the leaf spring is restrained with its one end on the housing in a predetermined position of rest, that the leaf spring is arranged with its other, free end in relation to the cover in such a way that, during the pivoting of the cover from the first position into the second position, the leaf spring is bent with the free end out of its position of rest, that the optical fiber in the connector runs parallel to a connector axis, that the cover can be pivoted about a pivot axis lying transversely in relation to the connector axis, and that the leaf spring in its position of rest on the housing rests on a supporting surface, the surface normal of which is oriented perpendicularly in relation to the pivot axis and runs parallel to the connector axis. The arrangement of the leaf spring parallel to the connector axis allows a comparatively long leaf spring, which has a favorable spring characteristic for the actuation of the cover, to be accommodated on the connector. The resting on a supporting surface leads to stable restraint of the leaf spring and to high functional reliability. 
   According to a preferred development of the configuration, for restraining one end of the leaf spring on the housing, the leaf spring rests with the end on the supporting surface on the housing and is held down on the supporting surface by hold-down devices arranged above the supporting surface on the housing and extending parallel to the supporting surface, it being possible for the leaf spring to be pushed in between the supporting surface and the hold-down devices. This configuration ensures that the leaf springs can be pushed very easily in between the supporting surface and the hold-down devices during assembly. 
   The leaf spring is preferably secured on the supporting surface against lateral displacement by fixing means. The housing of the connector and the assembly of the leaf spring are in this case particularly easily configured if the fixing means comprise two offsets in the housing, which prevent movement of the leaf spring in the direction of the connector axis, if the fixing means further comprise a stop for the cover protruding perpendicularly upward out of the center of the supporting surface and extending in the direction of the connector axis, if the leaf spring has a slit-like clearance which is open to one side and receives the stop when the leaf spring is inserted into the housing, and if the hold-down devices are arranged laterally on the stop. 
   In order that the leaf spring can be assembled more easily, it is of advantage if the slit-like clearance in the leaf spring has a funnel-shaped widening toward the open side. 
   The interaction between the leaf spring and the cover preferably takes place by actuating elements, in particular in the form of studs, which describe a circular path during pivoting of the cover, being arranged on the cover, and by the leaf spring resting with its free end on the actuating elements or studs and being deflected by the actuating elements or studs when the cover is pivoted from the first position into the second position. 
   In this connection, a bistable pivoting mechanism for the cover can be realized by the actuating elements or studs being arranged on the cover in such a way that a maximum deflection of the leaf spring is achieved when the cover is in a predetermined pivoting position, which lies between the first position and the second position, and by the cover being pressed into the second position by the leaf spring when it has exceeded the predetermined pivoting position while coming from the first position. 
   Another preferred configuration of the invention is characterized in that the leaf spring is fixedly arranged with its one end in the cover itself and, during the pivoting of the cover, slides with a free end along on a sliding surface formed on the housing in such a way that the cover is prestressed in the closing direction. This type of arrangement is particularly advantageous if, according to a development, the leaf spring is fastened to the cover in such a way that, when the cover is closed, it intercepts radiation emerging from the optical fiber and the part of the leaf spring that lies in the path of rays of the optical fiber when the cover is closed is set obliquely in relation to the optical axis of the optical fiber in such a way that radiation impinging on the leaf spring from the optical fiber is not reflected back into the optical fiber. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention is to be explained in more detail below on the basis of exemplary embodiments in conjunction with the drawing, in which 
       FIG. 1  shows in a perspective view, seen obliquely from the front, a preferred exemplary embodiment of a connector according to the invention in which the cover is located in the closed, first position; 
       FIG. 2  shows in a perspective view, seen obliquely from the rear, the connector from  FIG. 1  with the cover half swung open, with the maximum deflection of the leaf spring; 
       FIG. 3  shows in a representation comparable to  FIG. 1  the connector from  FIG. 1  with the cover in the completely swung-open, second position; and 
       FIG. 4  shows in a representation comparable to  FIG. 1  another preferred exemplary embodiment of a connector according to the invention, in which the leaf spring is arranged in the cover itself. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   In  FIGS. 1 to 3 , a preferred exemplary embodiment of a connector  10  according to the invention is reproduced in a perspective representation, the cover  17  provided on the connector  10  assuming different positions in the figures. The connector  10  has a housing  16  made of a suitable plastic, through which there runs in the longitudinal direction, along a connector axis  27  ( FIG. 2 ), a through-bore, which emerges to the outside at the rear end of the connector  10  in a first opening  23  ( FIG. 2 ) and at the front end in a second opening  25  ( FIG. 3 ). The cable with the optical fiber is introduced into the connector  10  through a kink preventer by being inserted into the rear, first opening  23 . From the front, second opening  25  there protrudes from the interior of the connector  10  a ferrule  24 , in the central bore of which the end of the optical fiber  26  is accommodated ( FIG. 3 ). For further details of the internal structure, reference should be made to the configuration given by way of example in  FIGS. 13 and 14  of the initially cited U.S. Pat. No. 6,142,676. 
   Formed onto the housing  16  at the rear end of the connector  10  is a latching arm  15 , which extends forward, parallel to the connector axis  27 , and can be bent elastically against the housing  16 . The latching arm  15  bears on its front, free end a latching hook  14 , with which it engages behind a latching edge in the coupling belonging to the connector  10  when the connector is inserted into the coupling. 
   At the front end of the connector  10 , a cover  17  is arranged pivotably about a pivoting axis  19  on the housing  16  by means of two pivoting arms  32 ,  33 . In the closed state ( FIG. 1 ), the cover  17  closes the front, second opening  25  and so protects the end face of the optical fiber  26  from soiling and damage. At the same time, laser light from the optical fiber  26  is prevented from being able to penetrate to the outside and damage the eye of a viewer. When the connector  10  is inserted into the coupling, the cover  17  is pivoted from the completely closed, first position, represented in  FIG. 1 , into the completely opened, second position, represented in  FIG. 3 , by an interaction between various actuating elements on the cover  17  and in the coupling. This takes place by a lug which is laterally attached in the coupling pressing against a first engagement surface  18 , which is formed laterally on the pivoting arms  32 ,  33  and above the pivot axis  19 . Lying opposite the first engagement surface  18  is a second engagement surface  18 &#39;, with which the lug of the coupling comes into engagement when the connector  10  is pulled out again from the coupling, and consequently pivots the cover  17  back again into the closed position. In the completely opened, second position of  FIG. 3 , the cover  17  butts against a stop  12 , which is formed on the housing  16  like a dorsal fin and has at the front end a stop face  20  ( FIG. 1 ) adapted to the shape of the cover. 
   According to the invention, the connector  10  is then provided with spring means, which include a leaf spring  11 . In principle, it is conceivable to form the leaf spring on the housing  16  as an integral part of the housing  16 . This would reduce the assembly effort to a minimum. In the embodiment of  FIGS. 1 to 3 , the leaf spring  11  is formed as a separate planar spring, comprising a metal sheet with good spring properties, which is fastened to the housing  16  of the connector  10 . For this purpose, a planar supporting surface  21 , which lies parallel to the connector axis  27  and on which the leaf spring  11  rests with the underside, is formed on the housing  16 . Laterally projecting hold-down devices  13 , which hold the leaf spring  11  down on the supporting surface  21 , are formed on the stop above the leaf spring  11 . The hold-down devices  13  extend outward, parallel to the supporting surface  21 , and are rounded off on the underside, in order on the one hand to facilitate assembly and on the other hand to facilitate resilient bending of the leaf spring  11 . The supporting surface  21  is bounded to the rear by a first offset  28 , which prevents displacement of the leaf spring  11  to the rear. A second offset  29  in the front region of the connector  10  prevents displacement of the leaf spring  11  to the front. The leaf spring  11  is fixed against lateral displacement by the stop  12 , which is received by a corresponding slit-like clearance  30  in the leaf spring  11 . The clearance  30  is open to the rear and has a funnel-shaped widening  31  at the open end, so that, to the rear, the leaf spring  11  has the shape of a two-pronged fork. The formation of the leaf spring  11  itself and the special type of fastening to the housing  16  makes the assembly of the leaf spring  11  very easy: with the cover  17  closed, it is pushed in a sliding manner to the rear on the supporting surface  21  with the side formed as a fork engaging around the stop  12 , it moving with the two prongs of the fork under the hold-down devices  13 . At the end of the pushing-in operation, the leaf spring  11  engages between the two offsets  28  and  29 . 
   The interaction of the leaf spring  11  with the pivotable cover  17  can best be seen in  FIG. 2 : formed on the cover  17  are the two pivoting arms  32 ,  33 , which engage laterally around the housing  16 , and by means of which the cover  17  is pivotably mounted at the pivot axis  19 . The leaf spring  11  comes to lie in a free space between the pivoting arms  32 ,  33 . Formed on the inner sides of the pivoting arms  32 ,  33  are inwardly protruding studs  22 , on which the leaf spring  11  rests with the front, free end. The studs  22  are positioned in such a way that, when the cover  17  is closed ( FIG. 1 ), and when the cover  17  is completely opened ( FIG. 3 ), the leaf spring  11  lies with its free end virtually parallel to the supporting surface  21  and is only slightly deflected, in order to ensure that the cover  17  remains stably in the extreme positions. When the cover  17  pivots between these two extreme positions, the studs  22  define a circular path about the pivot axis  19 , on which they elastically deflect or raise the free end of the leaf spring  11  until, according to  FIG. 2 , in a predetermined intermediate position in which the studs  22  are approximately vertically above the pivot axis  19 , the maximum extend of the leaf spring  11  is reached. Before this intermediate position, the leaf spring  11  prestresses the cover  17  in the closing direction; behind the intermediate position, the leaf spring  11  presses the cover into the completely opened position of  FIG. 3 . The cover  17  with the formed-on pivoting arms  32 ,  33  may be produced from a plastic. However, it is also conceivable to form the cover and the pivoting arms from a metal, in order to safely shield laser radiation emerging from the optical fiber  26  even in the case of higher intensities. In this case, it is expedient to set the inner side of the cover  17  obliquely in relation to the optical axis of the optical fiber  26 , in order to avoid reflection of the radiation back into the fiber. 
   Another exemplary embodiment of an optical connector according to the invention is reproduced in  FIG. 4 . The connector  34  has a housing  16  which is comparable to the connector  10  from  FIG. 1 , with a comparable latching arm  15  and latching hook  16  for latching in the coupling. In the case of this exemplary embodiment, too, the cover  17  which can pivot about a transversely lying pivot axis  19  is arranged at the front end of the connector  34 . Formed in turn on the cover  17  are pivoting arms, only one pivoting arm  32  of which can be seen. The engagement surfaces  18  and  18 ′ have the function already described further above in connection with  FIG. 1 . The prestress of the cover in the closing direction is undertaken here by a leaf spring  35 , which is fastened to the cover  17  itself. The leaf spring  35  is bent like a V. With one leg of the V, it is pushed into a clearance on the front side of the cover  17  and held in this way. The other, free leg of the V protrudes upward between the cover  17  and the end face of the housing  16  and undertakes the spring function. It is laterally guided by two bounding walls  37 ,  38  formed onto the housing  16 . 
   When the cover  17  is swung open from the closed position shown in  FIG. 4 , the leaf spring  35  is pivoted along with it. The free leg of the leaf spring  35  slides along on an outwardly curved sliding surface  36  of the housing  16 . This sliding surface  36  is designed in its curvature in such a way that the spring stress of the leaf spring  35  increases as the cover  17  swings open. A prestress in the closing direction is correspondingly obtained for the cover  17 . If the curvature of the sliding surface  36  is additionally designed in such a way that the spring stress decreases again toward the end of the swinging-open operation, a bistable behavior is obtained in the same way as in the case of the exemplary embodiment of  FIG. 1 , i.e. the cover reaches a stable end position with corresponding spring prestressing both when it is completely closed and when it is completely opened. 
   The advantage of the spring configuration shown in  FIG. 4  is obvious in particular for those connectors in which laser radiation can emerge with relatively great power from the end of the optical fiber. When the cover  17  is closed, the (metallic) leaf spring  35  is located here directly in the path of rays of the optical fiber and effectively blocks the light emerging from the optical fiber. If, in addition, the part of the leaf spring  35  that lies in the path of rays of the optical fiber  26  when the cover  17  is closed is set obliquely in relation to the optical axis of the optical fiber  26  in such a way that radiation impinging on the leaf spring  35  from the optical fiber is not reflected back into the optical fiber, the further advantage is obtained that reflection-related interferences in a circuit connected to the optical fiber are reliably avoided when the cover  17  is closed. The shielding of the laser radiation emerging from the optical fiber can be improved still further if metal inserts which intercept the laterally emerging radiation are provided laterally on the inner side in the cover  17 .