Abstract:
A fiber-optical connector system, including a fiber-optical connector and a coupling into which the connector can be inserted to establish an optical connection. The connector has a housing that extends along an axis and into which an optical fiber is arranged with the axis projecting with one end from the face of the housing. Means exist to cover the end of the optical fiber and protect the end of the optical fiber from any effects from the exterior when the connector is not inserted and to release the end of the optical fiber projecting from the housing when the connector is inserted in the coupling. A protection device for the connector system may be derived by configuring the cover means with a first cover element that protects the end of the optical fiber in the axial direction.

Description:
FIELD OF THE INVENTION 
     The present invention relates to the field of fiber optics and, more specifically, to a fiber-optical connector system. 
     DESCRIPTION OF THE PRIOR ART 
     In the case of fiber-optical connector systems, in which it is usual for two optical fibers to be releasably connected to each other by insertion of two connectors into a coupling from two sides, the end faces of the two fibers to be connected must be brought into contact in such a way that a transfer of the optical signals that is as free as possible from losses can take place between the two fibers. For this purpose, the ends of the optical fibers, which are often adhesively embedded in ferrules, enter from both sides into a guiding sleeve provided in the coupling (see for example FIG. 10 of EP-B1-0 570 652 or FIGS. 20 and 21 of WO-A1-00/16145). In order that this can take place, the ends of the optical fibers or ferrules must be freely accessible at the end of the insertion operation. 
     On the other hand, it is necessary to prevent the ends of the optical fibers from being soiled when the connectors are not inserted in the coupling. In principle, it is conceivable for this purpose to provide protective caps, which are pushed manually over the free ends of the connectors. In order to avoid incorrect operation, however, a change has taken place in favor of providing the connectors with covering means which open automatically when the connector is inserted into the coupling, and also close again automatically when the connector is pulled out of the coupling. In addition, the coupling means are set up in such a way that a light beam emerging from the free fiber ends is reliably covered and cannot cause any damage. 
     In WO-A1-00/16145 (ADC) there is a description of a fiber-optical connector system which comprises a connector and a coupling. The connector, in which the optical fiber guided in the interior may optionally be arranged with its end freely accessible (FIGS. 5, 9) or in a ferrule (FIGS. 10, 13), is equipped with a covering flap. The covering flap is mounted pivotably about a fixed pivot axis. It pivots on insertion of the connector into the coupling, when an actuating cam arranged in the coupling comes into engagement with a slotted guideway on the covering flap. The covering flap and its pivoting region are designed in such a way that, after pivoting up, an end portion of the optical fiber or of the ferrule enclosing it projects freely forward out of the connector housing and can enter a sleeve-like guiding part arranged in the coupling. However, this has the consequence that comparatively considerable space is required for accommodating the covering flap on that side toward which the covering flap pivots up. This also applies to a similar known solution with a fixed pivot axis, as disclosed in U.S. Pat. No. 5,379,362. 
     Another known solution. (EP-B1-0 570 652, Diamond S. A.) provides a covering flap which, when the connector is inserted into the coupling, in a first phase is pivoted up by about 90° and in a second, subsequent phase is pushed back rearward parallel to the pivot axis, in order to release completely the end of the ferrule projecting from the connector housing. Although the combined pivoting and pushing movement has the effect that the space requirement for the covering flap is less than in the case of the pure pivoting movement of WO-A1-00/16145, the combined movement represents a comparatively complicated sequence of movements, which requires high precision and is susceptible to malfunctions. In addition, here—as in the case of the solution according to WO-A1-00/16145—the covering flap can be inadvertently opened and remain open even when a connector is not inserted. 
     A further known solution for a covering or protecting mechanism operating automatically on insertion is described in GB-A-2,112,173 (Thomas and Betts Corp.). In the case of this fiber-optical connector, the fiber lies with its end in a guiding sleeve which projects forward from the connector housing and can be pushed back against the pressure of a spring (44 in FIG. 1 or 144 in FIG. 3), which at the front end has a bore for the fiber. Provided laterally on the outside of the guiding sleeve is a covering in the form of a flexible sheet-metal strip. In the non-inserted state, the covering projects with the front end over the bore in such a way that the bore is closed. When the connector is inserted into a coupling part, the covering is displaced against a spring action (rearward or transversely) in such a way that the bore in the guiding sleeve is released. A disadvantage of this solution is that the guiding sleeve is not protected against mechanical effects when a connector is not inserted. Furthermore, the laterally provided sheet-metal strip prevents the guiding sleeve from being used for centering the connection when the connector is inserted. A force oriented transversely to the direction of insertion is also exerted on the guiding sleeve when the covering is actuated, and can easily lead to malfunctions. In addition, this protective mechanism is not suitable for connectors in which a ceramic ferrule into which the fiber is adhesively embedded by the end is provided instead of the guiding sleeve. 
     SUMMARY OF THE INVENTION 
     It is therefore the object of the invention to provide a connector system which avoids the disadvantages of known systems and, in particular with a simple and space-saving construction of the covering mechanism, is distinguished by high functional reliability. 
     The object is achieved by the features of claim  1  in their entirety. The essence of the invention is to divide the covering means into a first covering element, which protects the end of the optical fiber in the axial direction and can be displaced transversely to the axis, and a second covering element, which protects the end of the optical fiber projecting from the housing in the radial direction and can be displaced rearward parallel to the axis, and which has a first passage for the end of the optical fiber, the first passage being able to be closed by the first covering element. The division has the effect of producing simplified movement sequences for the two covering elements. At the same time, the division permits a space-saving arrangement and separate optimization of the functions. 
     The covering mechanism becomes particularly compact if, according to a first preferred refinement of the invention, the first covering element is arranged displaceably on the second covering element, if the first covering element is formed as a shutter, which is mounted displaceably transversely to the axis in a guideway formed in the second covering element, if, outside the region of the first passage, the guideway bends around in an arc rearward in a direction lying parallel to the axis, and if, for opening and closing the shutter, the shutter is displaced with its rear end parallel to the axis. 
     The automatic closing of the shutter is preferably brought about by the shutter being biased in the closed direction by a spring element, preferably in the form of a compression spring. 
     A particularly simple and effective mechanism for opening the shutter is obtained if, according to another preferred refinement of the invention, the shutter is fastened by its rear end to a slide, which is mounted displaceably in the direction of the axis in the housing of the connector, and if engaging means by which the slide is displaced rearward when the connector is inserted into the coupling are provided on the coupling and on the slide. In this case, the engaging means preferably comprise two actuating cams arranged on the inner sides of the side walls of the coupling and also two hook-shaped drivers, which are arranged on the sides of the slide and come into engagement with the actuating cams when the connector is inserted into the coupling. 
     For reliable prevention of a disturbing reflection of light through the closed shutter back into the optical fiber, it is of advantage if, in the region of the first passage, the guideway runs slightly at an angle to the axis. 
     The covering mechanism of the invention can be realized particularly simply if the second covering element is formed as a flap-shaped cover, and the guideway for the shutter is formed between the cover and a holder which is provided with a second passage and is fitted into the cover. 
     For opening the second covering element, in the coupling there is preferably a stop against which the second covering element or the cover butts, and by which the second covering element or the cover is pushed back rearward, thereby releasing the end of the optical fiber, when the connector is inserted into the coupling. 
     For closing the second covering element, in the coupling and on the second covering element or the cover there are preferably latching means which latch the second covering element or the cover to the coupling when the connector is completely inserted into the coupling, and securely hold the second covering element or the cover in the coupling when the connector is pulled out of the coupling, until the relative displacement between the second covering element or the cover and the housing of the connector causes the end of the optical fiber to be covered again in the radial direction. The latching means preferably comprise a detent provided on the second covering element or cover and also a closure flap, the closure flap being pivotably arranged in the coupling by means of a pivot bearing lying transversely to the axis and closing the coupling when the connector is not inserted, and the closure flap being pivoted up and latching with its free end behind the detent by insertion of the connector into the coupling. 
    
    
     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 a longitudinal section through a connector according to a preferred exemplary embodiment of the invention in the non-inserted state with the covering device closed; 
     FIG. 2 shows in an exploded representation the individual parts of the connector according to FIG. 1; 
     FIG. 3 shows in a representation comparable to FIG. 1 the connector from FIG. 1 inserted into the coupling, with the covering device opened; 
     FIGS. 4 and 5 show in another sectional representation the function of the locking mechanism acting between the two covering elements of the covering device. 
    
    
     DESCRIPTION OF THE INVENTION 
     FIG. 1 shows a longitudinal section through a connector according to a preferred exemplary embodiment of the invention in the non-inserted state with the covering device closed. The connector  10 , the individual parts of which are also represented with the same reference numerals in FIG. 2, has an elongate housing  11 , which is produced as an injection-molded part from a suitable plastic and extends in the direction of an axis  49 . The axis  49  is at the same time the optical axis for the optical fiber (not shown in FIG. 1) and, in addition, indicates the direction of insertion in which the connector  10  is inserted. 
     Running coaxially in relation to the axis  49  through the housing  11  is a bore  12 , which receives the optical cable or the optical fiber. At the front end (on the left in FIG. 1) and at the rear end (on the right in FIG. 1) of the connector  10 , the bore  12  respectively goes over into a widened portion  17  and  18  with an enlarged inside diameter. Into the first widened portion  17  there projects a cylindrical ferrule  23 , in the central bore  24  of which the end of the optical fiber is adhesively embedded in such a way that the end face of the fiber terminates with the convex end face of the ferrule  23 . 
     The ferrule  36  is seated with the rear end in a ferrule holder  22 , which is mounted displaceably in the direction of the axis  49  in the bore  12  and can be pushed rearward against the pressure of a first compression spring  25 . Fitted into the second widened portion  18  is a spindle  21 , the sleeve-shaped rear portion of which is used for fixing the optical cable and for pushing on an anti-kinking sleeve (comparable to FIG. 14 of WO-A1-00/16145). Also formed on at the rear end of the housing  11  is a forwardly extending, flexible latching arm  19 , which serves for fixing the inserted connector  10  (see FIG.  3 ). The latching arm  19  has at its front free end two latching hooks  20 , the function of which is discussed in more detail further below in conjunction with FIG.  3 . 
     Provided at the front end of the connector, in the region of the ferrule  23 , is a protecting and covering device, which substantially comprises two covering elements. The one covering element is a cap-shaped cover  30  with a central passage ( 36  in FIG.  2 ). The cover  30  is mounted displaceably in the direction of the axis  49  at the front end of the housing  11  and is pushed back rearward over the ferrule  23 , thereby releasing the front end of the ferrule  23 , when the connector  10  is inserted into the associated coupling ( 40  in FIG.  3 ). 
     The cover  30 —when it is not pushed back—protects the ferrule  23  projecting from the widened portion  17  in the radial (lateral) direction. For the protection of the ferrule  23  in the axial direction (from the front), a shutter  32  (see also FIG. 2) is provided as the other covering element in the form of a rectangular, flexibly bendable sheet-metal strip, which is guided on the cover  30  in a guideway  31 . The guideway  31  is formed by a holder  29  of an adapted shape, with a comparable passage ( 35  in FIG. 2) being fitted into the cover  30  from the rear, thereby maintaining a small distance which corresponds to the width of the guideway  31 . 
     In the region of the first passage  36 , the guideway  31  runs substantially perpendicularly to the axis  49 . However, it deviates from the perpendicular to the extent that a reflection of light through the shutter  32  back into the optical fiber is reliably prevented. Outside the region of the first passage  36 , the guideway  31  bends around in an arc rearward in a direction lying parallel to the axis  49 . The shutter  32  guided in the guideway  31  is correspondingly bent. This achieves the effect that opening and closing of the shutter  32  is performed by displacing the rear end of the shutter  32  parallel to the axis  49 . 
     The shutter  32  is fastened by the rear end to a slide  26 , which is mounted displaceably in the axial direction in the upper part of the housing  11  in a slot-shaped clearance  13  and can be pushed back rearward against the pressure of a second compression spring  27 . The slide  26  has on the upper side a holding cam  28 , which reaches through a corresponding hole  48  in the shutter  32 . Formed on two opposite sides of the slide  26  are flat arms  33 , which project to the outside through lateral slots  14  in the housing  11 . Formed on the outer ends of the arms  33  are hook-shaped drivers  34 , which come into engagement with actuating cams ( 43  in FIG.  3 ), fixedly provided on the inner walls of the coupling  40 , when the connector  10  is inserted into the coupling  40 . The slide  26  is consequently pushed back relative to the housing  11  on insertion and the shutter  32 , pulled back with the slide  26 , releases the first passage  36 . If the connector  10  is pulled out of the coupling  40  again, the compression spring  27  pushes the slide  26  back in the forward direction and the shutter  32  closes the first passage  36  again. 
     The actuation of the cover  30 , which—as explained further below on the basis of FIGS.  4  and  5 —is performed in accordance with the actuation of the shutter  32 , can be explained on the basis of FIG. 3, which shows a connector  10  completely inserted into the coupling  40 . Of the coupling  40 , only that part (the right-hand part) which is necessary for the connector  10  inserted from the right of the connector system  47  is represented in FIG.  3 . For a second connector, inserted from the left, there is also a second, mirror-inverted (left-hand) part (see for example FIG. 21 of WO-A1-00/16145). The coupling  40  has in the center a bush mounting  41 , which is coaxial to the axis  49  and into which a ceramic sleeve for guiding the ferrules of the two connectors can be inserted. The bush mounting  41  is held by a wall which is arranged perpendicularly in the centre and forms a stop  42  for the cover  30  of the inserted connector  10 . If the connector  10  is then inserted into the coupling  40 , firstly the lateral actuating cams  43  (depicted in FIG. 3 for clarification—although they are not visible) come into engagement with the drivers  34  of the slide  26 . The slide  26  moves back in the clearance  13  and draws up the shutter  32  over the first passage  36 . The cover  30  is in this phase hindered in a drawing-back movement by a locking mechanism described further below. Once the first passage  36  is free and the locking is unlocked, as it is inserted further the connector  10  butts with the cover  30  against the stop  42  of the coupling  40  and the cover  30  is pushed back, until the front end of the ferrule  32  is free, as shown in the representation in FIG.  3 . 
     For the pushing forward of the cover from the pushed-back position shown in FIG. 3, a special latching mechanism, which is represented in FIG. 3, is provided. Belonging to this latching mechanism are two detents  38 , arranged on the upper side of the cover  30 , and a closure flap  45 . The closure flap  45  is articulated pivotably in the interior of the coupling  40  by means of a pivot bearing  46  oriented transversely to the axis  49 . When the connector  10  is inserted into the coupling  40 , the closure flap  45  is pivoted up against the pressure of a spring and, after complete insertion of the connector  10 , latches with the free edge, lying on a supporting surface  39 , behind the detents  38  (FIG.  3 ). If the connector  10  is pulled out of the coupling  40  again, the latched closure flap  45  keeps the cover  30  fixed or back, until it is lifted over the detents  38  by an unlocking cam  16 , which is formed on an attachment  15  of the housing  11  and slides back with the housing  11 , and releases the cover  30 . In order that the unlocking cam  16  can move freely in relation to the cover  30 , a clearance  37  is provided between the detents  38 . 
     For the locking of the inserted connector  10  in the coupling  40 , the already mentioned flexible latching arm  19  is provided with the latching hooks  20 , arranged at its free end. When the connector is inserted, the latching arm  19  latches with the latching hooks  20  behind two detents  44  formed on the inner edge of the coupling  40 . For unlocking, the latching arm  19  must then be pressed down, until the latching hooks  20  come free from the detents  44 . 
     The already mentioned locking of the cover  30  by the slide  26  can best be explained on the basis of another sectional representation, as represented in FIGS. 4 and 5 for the locked and unlocked states. Essential elements of the locking mechanism are two locking levers  50  (FIGS. 2,  4  and  5 ), which are formed on the housing  11 , extend parallel in the axial direction, can be deflected resiliently downward, are arranged on the lower inner edges of the slots  14  and respectively bear a cam  51  on the upper side. Left free underneath the locking levers  50  there is respectively a slot-shaped intermediate space  52 , which, when the cover  30  is pushed back, can receive tongues  53  formed on the holder  29  and designed in such a way as to fit the intermediate space  52 . 
     In the unplugged state of the connector  10 , as represented in FIG. 4, the slide  26  is located with its arms  33  directly above the cams  51  of the locking levers  50 . As a result, the locking levers  50  are deflected resiliently downward and prevent the tongues  53  of the holder  29  from entering the intermediate spaces  52  lying thereunder. The holder  29 , and consequently also the cover  30 , are thereby effectively prevented from yielding in this phase. 
     If, when the connector  10  is inserted, the slide  26  with the shutter  32  is pushed back in the way described further above to the extent that the passage  36  for the ferrule  23  is released, the cams  51  are released and the locking levers  50  can pivot back into their axially parallel position of rest. The intermediate spaces  52  lying thereunder are then released, so that the holder  29  can enter with its tongues  53  into the intermediate spaces  52  and the cover  30  can correspondingly move back and release the ferrule  23  (FIG.  5 ). 
     List of Designations 
     
       
         
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 10 
                 connector 
               
               
                   
                 11 
                 housing 
               
               
                   
                 12 
                 bore 
               
               
                   
                 13 
                 clearance (slot-shaped) 
               
               
                   
                 14 
                 slot 
               
               
                   
                 15 
                 attachment 
               
               
                   
                 16 
                 unlocking cam 
               
               
                   
                 17, 18 
                 widened portion 
               
               
                   
                 19 
                 latching arm 
               
               
                   
                 20 
                 latching hook 
               
               
                   
                 21 
                 spindle 
               
               
                   
                 22 
                 ferrule holder 
               
               
                   
                 23 
                 ferrule 
               
               
                   
                 24 
                 bore 
               
               
                   
                 25, 27 
                 compression spring 
               
               
                   
                 36 
                 slide 
               
               
                   
                 20 
                 holding cam 
               
               
                   
                 29 
                 holder 
               
               
                   
                 30 
                 cover 
               
               
                   
                 31 
                 guideway 
               
               
                   
                 32 
                 shutter 
               
               
                   
                 33 
                 arm 
               
               
                   
                 34 
                 driver (hook-shaped) 
               
               
                   
                 35, 36 
                 passage 
               
               
                   
                 37 
                 clearance 
               
               
                   
                 38, 44 
                 detent 
               
               
                   
                 39 
                 supporting surface 
               
               
                   
                 40 
                 coupling 
               
               
                   
                 41 
                 bush mounting 
               
               
                   
                 42 
                 stop 
               
               
                   
                 43 
                 actuating cam 
               
               
                   
                 45 
                 closure flap 
               
               
                   
                 46 
                 pivot bearing 
               
               
                   
                 47 
                 connector system 
               
               
                   
                 48 
                 hole 
               
               
                   
                 49 
                 axis 
               
               
                   
                 50 
                 locking lever 
               
               
                   
                 51 
                 cam 
               
               
                   
                 52 
                 intermediate space (slot-shaped) 
               
               
                   
                 53 
                 tongue (rigid)