Abstract:
A coupling system includes an optical plug-in connector, a coupling partner and a retaining element. The housing of the plug-in connector is provided with a sliding key and with two springy detent limbs which include a detent nose for engaging with the coupling partner. In order to receive the plug-in connector, the coupling partner is provided with a plug inlet which has recesses that correspond to the detent noses of the plug-in connector. A retaining element includes a laterally displaceable outer housing and an inner housing that is pivotally arranged therein. A locking element is provided as a two-limb lever that is arranged on the inner housing and that serves to lock the plug-in connector in the retaining element. When inserting the plug inlet, this locking is released once the plug-in connector and plug inlet are engaged with one another.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
         [0001]    This application is a continuation of copending International Application No. PCT/DE01/00088, filed Jan. 5, 2001, which designated the United States and was not published in English.  
         BACKGROUND OF THE INVENTION  
         [0002]    Field of the Invention  
           [0003]    The invention lies in the field of optical elements and is applied to mechanical connecting devices for optical fibers in which a plurality of optical fibers, which are arranged in parallel to one another and which end in a plug-in connector, are connected to a coupling partner arranged on a circuit board. Using a holder, this plug-in connector is arranged in a housing wall. Coupling partners can be, for example, optical transmitting and/or receiving modules or can be formed by identical or similar plug-in connectors.  
           [0004]    European Patent Application EP 0807 837 A1 teaches a known multichannel optical coupling configuration of this type in which one or two plug connectors are assigned to a coupling partner, likewise including one or two plug-in connectors, by using a holder which is arranged in a housing wall (back panel). This holder includes an outer housing having four walls that run toward one another at right angles and an inner housing arranged in the outer housing such that it can be moved axially, that is to say in the Z direction, and at right angles thereto, that is to say in the X/Y direction. The inner housing is used to accommodate and axially fix one or both plug-in connectors, which each contain a multichannel optical fiber end piece arranged in a housing in a known way. This multichannel optical fiber end piece is referred to as a “ferrule” and is arranged at the end of a multichannel optical fiber cable (See also Issued German Patent DE 195 39 549 C1, International Publication WO 97/34176, European Patent application EP 0803 749 A1, and European Patent application EP 0803 748 A1). A coupling partner is arranged on a circuit board using a connector housing. The connector housing can be plugged into the outer housing of the holder, to which end both housings are provided with guide surfaces and interengaging guide grooves and webs. The connector housing is also provided with latching hooks, arranged in a resilient manner, which engage in corresponding openings in the inner housing of the holder and in this way brace the optical fiber end pieces (ferrules) of the plug-in connectors to be coupled axially against each other. The latching and locking elements arranged in the inner region of the holder make disassembling this coupling configuration more difficult.  
           [0005]    It is further known, to provide diodes as coupling partners for an optical plug-in connector arranged at the end of an optical fiber cable. These diodes are arranged on a circuit board and a plug-in inlet is provided in order to retain the plug-in connector (See U.S. patent application No. 5,138,680 and German Patent Application DE 42 05 568 A1). In a coupling configuration which is also known, the plug-in connectors, which are substantially identically designed and arranged in mirror-image fashion in relation to each other, are connected to each other within a two-part adapter (See European Patent Application EP 0712 015 A2). In another known configuration, in each case, a plurality of plug-in connectors are assigned one half of a two-part coupling housing. The two differently designed halves of the coupling housing interengage with finger-like guide wings and corresponding guide grooves and also with retaining collars (See International Publication WO 97/34 176).  
         SUMMARY OF THE INVENTION  
         [0006]    It is accordingly an object of the invention to provide a multichannel optical coupling configuration which overcomes the above-mentioned disadvantages of the prior art apparatus of this general type.  
           [0007]    With the foregoing and other objects in view there is provided, in accordance with the invention, a multichannel optical coupling configuration, which includes a plug-in connector, a coupling partner arranged on a circuit board and a holder to be arranged in a recess in a housing wall (back panel) to guide and retain the plug-in connector and to guide the coupling partner. A multichannel optical fiber end piece (ferrule) is arranged in an axially resilient manner in the housing of the plug-in connector and the coupling partner has a plug-in inlet to connect to the plug-in connector, in such a way that the coupling configuration, while being easy to mount and disassemble, permits the compensation even of relatively large tolerances between the board and the back panel transversely with respect to the plug-in direction, as well as the compensation of angular tolerances.  
           [0008]    In order to achieve this object, the invention uses some design features which are known for coupling configurations of this type. To some extent, these features are placed in a different operative conjunction and new design features are added. These measures lead to a coupling configuration in which the plug-in connector is locked in the holder such that it can be unlocked in a simple way, and in which the coupling partner can be locked accurately in position with the plug-in connector. In addition, the housing wall carrying the holder is completely relieved of plug forces, and only compressive and tension forces have to be exerted on the plug-in connector or the coupling partner in order to couple and uncouple coupling partner and the plug-in connector. This is achieved by using a special configuration of the holder, including the outer and inner housing, and the parts of the plug-in connector and the coupling partner that come into an operative connection with the inner housing of the holder.  
           [0009]    Accordingly, first of all the holder includes an outer housing, which is arranged such that it can be displaced at right angles to the plug-in direction, and an inner housing. The inner housing is arranged such that it can rotate in the outer housing. At the same time, in order to retain the plug-in connector in the holder on the inner housing, a locking element designed as a two-armed lever is mounted. One lever arm of the locking element is subject to the action of a spring. Then, in order to latch the plug-in connector to the coupling partner, the housing of the plug-in connector is provided with at least one resilient latching arm having a latching lug, and the coupling partner is provided with a recess arranged in the plug-in inlet to accommodate the latching lug. For the invention, it is also important that the plug-in inlet of the coupling partner is provided with fingerlike guide elements which extend in the plug-in direction, which have operative faces arranged in a stepped manner. Guide faces are assigned on the inner housing of the holder to couple the coupling partner in an accurately fitting manner to the plug-in connector, and also operative faces for unlocking the locking element on the lever arm of the locking element which is subject to the action of a spring. The recess arranged in the plug-in inlet and the operative faces on the finger-like guide elements of the plug-in inlet are staggered in the plug-in direction in such a way that when the coupling partner is joined to the plug-in connector retained in the holder, the locking element arranged in the holder is unlocked after the latching lug of the plug-in connector has latched in the recess in the plug-in inlet.  
           [0010]    A coupling configuration configured in this way permits adequate compensation of tolerances between the parts arranged in the housing wall and the parts of the coupling configuration arranged on the circuit board. It is also possible for angular errors with regard to the configuration of the coupling partner on the circuit board to be compensated for by using the pivotable configuration of the inner housing of the holder. The configuration of the locking element as a two-armed, spring-loaded lever permits complete relief of the load on the housing wall from the forces acting between the plug-in connector and the coupling partner in the coupled state, and also enables secure retention of the plug-in connector when the coupling is released. It is possible nevertheless for this retention to be released in a simple way.  
           [0011]    In order to be able to implement the latching and locking functions provided when the plug-in connector and the coupling partner are guided together, with the most compact design of the coupling configuration possible, in a development of the invention, the plug-in connector housing is of a flat design and one of its broad sides has a sliding key for the correct lateral assignment to the holder. Each of the narrow sides of the plug-in connector housing has a resilient latching arm with a latching lug. Furthermore, the locking element mounted in the inner housing is assigned to a broad side of the plug-in connector and is configured as a rocker which extends in the plug-in direction. The end of the rocker that is subject to the action of the spring, is designed as a locking lug to engage in a recess extending in the plug-in direction in the plug-in connector housing. The other end of the rocker is freely accessible. In this connection, the locking lug of the locking element has wing-like extensions that run transversely with respect to the plug-in direction. Inclined faces of the locking element, that are for unlocking the locking element, are assigned to the finger-like guide elements of the plug-in inlet of the coupling partner. The recesses in the plug-in inlet of the coupling partner are dimensioned in the plug-in direction such that they permit a relative movement between the plug-in inlet and the plug-in connector housing in the latched state. Finally, the distance, in the plug-in direction, from the latching edge of the respective recess in the plug-in inlet to the inclined faces on the finger-like guide elements of the plug-in inlet is less than the sum of the distances provided in the plug-in direction from the latching lugs of the plug-in connector to the recess provided in the plug-in connector housing for the locking element, and the distance from the recess for the locking element to the wing-like extensions.  
           [0012]    The intended compact design is further improved if the recess provided in the plug-in connector for the access of the locking lug is provided in a web forming the sliding key.  
           [0013]    In order also to ensure automatic unlatching of the plug-in connector and the coupling partner when the new coupling configuration is being released under the action of tensile forces, in a further refinement of the invention, each latching arm of the plug-in connector housing is provided with a web which is arranged behind the latching lug in the plug-in direction and which runs transversely with respect to the plug-in direction. An inclined plane is assigned in order to unlatch the latching lug on the inner housing of the holder. The distance provided, in the plug-in direction, from the recess in the plug-in connector housing to the web is greater than the distance provided, in the plug-in direction, from the spring-loaded end, designed as a locking lug, to the lever designed as a rocker from the inclined plane provided in the inner housing.  
           [0014]    A configuration of this type, with which the unlatching between the plug-in connector housing and the coupling partner, during the release of the coupling, is coordinated with the locking operation between the plug-in connector and the holder, is of special advantage when two or more plug-in connectors or coupling partners are arranged, since all of the coupling partners are unlatched without manual intervention as they are pulled out of the circuit board.  
           [0015]    In a further refinement of the invention, the outer housing of the holder can be fixed in the housing wall by a supporting clip. This enables the coupling configuration to be easily mounted.  
           [0016]    When a plurality of plug-in connectors are assigned to one housing wall, in order to be able to arrange the plug-in connectors in a space-saving manner as much as possible, it is advantageous if two plug-in connectors and the two holders are arranged in a mirror image fashion in relation to each other in the same recess in the housing wall. This space-saving configuration can be further perfected if the two associated coupling partners, which for example, are formed as optical receiving and/or transmitting modules, but which can also be formed as plug-in connectors, are arranged in a mirror image fashion on the two sides of the circuit board. If in this connection, the outer housing of the holder is constructed from a plastic part and a sheet-metal part in such a way that the mutually facing wall parts of two holders arranged in the same recess in the housing wall consist of thin sheet-metal parts, then this configuration leads to a minimum spacing between the two outer housings, which makes a high packing density possible for the coupling partners arranged on the circuit board. In this way, a distance between the optical axes of two adjacent coupling partners of less than 9 mm can be achieved.  
           [0017]    In order to be able to optimally align the plug-in connectors that are locked in the holder in relation to the coupling partners that are arranged on the circuit board, both in the plug-in direction and also transversely thereto, a flat design of the finger-like guide elements of the plug-in inlet is recommended. The tips of the guide elements are provided with bevels serving to align the holder. The guide face, pointing outward, of a guide element is provided with a web-like elevation that is arranged to be set back opposite the respective finger tip. The end of the elevation facing the finger tip has an inclined face used to engage in the locking element.  
           [0018]    The intended optimum alignment also requires a specific configuration of the holder, in particular of its inner housing. First of all, in a further refinement of the invention with respect to the outer housing, it is expedient that the outer housing includes a U-shaped plastic part and a likewise U-shaped sheet metal part placed on the plastic part in the manner of a clip. The sheet-metal part is provided with latching tongues to retain the outer housing of the supporting clip. In order at the same time to ensure the preconditions for the pivotable configuration of the inner housing in the outer housing, the sheet-metal part is provided with a pin and the plastic part is provided with a hole. This pin and this hole are operatively connected to a hole and a pin which are arranged on two opposite walls of the inner housing, which includes a plastic part with a substantially box-like outer contour. In addition, guide faces formed with webs and guide grooves for the plug-in connector and for the plug-in inlet of the coupling partner are also provided on the two opposite walls of the inner housing. In order to form these guide faces and guide grooves, there are two webs of an L-shaped cross section, which are carried by one wall of the inner housing and which between them, with the outer L-shaped faces, form a guide groove for the sliding key in the form of a web arranged on the plug-in connector housing. At the same time, the inner L-shaped faces of the webs, form guide faces for the fingerlike guide elements of the plug-in inlet. A further web for aligning the finger-like guide elements is arranged laterally beside the L-shaped webs in each case.  
           [0019]    The most compact and easy-to-mount configuration of the coupling configuration is provided by using pins to mount the locking element, which is designed as a rocker, in the L-shaped webs in such a way that the locking lug projects into the guide groove for the sliding key.  
           [0020]    In order that during the insertion of the plug-in inlet of the coupling partner, the movably arranged holder can assume the optimum position for joining the coupling partner and the plug-in connector as snugly as possible, that is to say without the risk of canting, it is advantageous if the webs that are arranged in the inner housing of the holder begin behind the pins and holes that are provided for pivotably mounting the inner housing, as viewed in the plug-in direction of the coupling partner. The force action points for aligning the inner housing in this case lie behind the pivot axis of the inner housing, as viewed in the plug-in direction.  
           [0021]    Other features which are considered as characteristic for the invention are set forth in the appended claims.  
           [0022]    Although the invention is illustrated and described herein as embodied in a multichannel optical coupling configuration, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.  
           [0023]    The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0024]    [0024]FIG. 1 is a perspective view of the partners of the coupling configuration not yet joined, and specifically shows two plug-in connectors, a part of a housing wall with a holder configured thereon, and a part of a circuit board with two coupling partners in the form of optoelectronic modules;  
         [0025]    [0025]FIG. 2 is a perspective view of the same parts of the coupling configuration as shown in FIG. 1, but they are in a joined state—part of the holder has been cut away in order to show the interplay of the three parts of the coupling configuration;  
         [0026]    [0026]FIG. 3 is a front perspective view of a plug-in connector;  
         [0027]    [0027]FIGS. 4 and 5 show perspective views of two sectioned halves of longitudinal sections through the holder;  
         [0028]    [0028]FIG. 6 shows the outer housing;  
         [0029]    [0029]FIG. 7 shows a perspective view of the inner housing of the holder;  
         [0030]    [0030]FIG. 8 is a perspective view of the inner housing of the holder, opened in the area of the locking element;  
         [0031]    [0031]FIG. 9 is a perspective view of a plug-in inlet shown in FIG. 1;  
         [0032]    [0032]FIGS. 10 and 11 show a horizontal and a vertical longitudinal section of a plug-in connector locked in the holder with the coupling partner not coupled in order to illustrate the distances required for the locking and latching operation; and  
         [0033]    [0033]FIG. 12 shows two further horizontal longitudinal sections to illustrate the distances required for the unlocking operation.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0034]    Referring now to the figures of the drawing in detail and first, particularly, to FIG. 1 thereof, there is shown two identically designed plug-in connectors  1 , which are in each case mounted at the end of an optical cable  2  and are provided for the purpose of being plugged into a holder  20  which is arranged in a recess in a housing wall (back plane)  21 . Arranged on the opposite side are two likewise identically designed coupling partners  60  on two opposite sides of a circuit board  72 . The coupling partners in each case include an electro-optical module  61  and a plug-in inlet  62  fixed thereto. The plug-in inlet  62  has a cross section with a box-like configuration to accommodate a plug-in connector  1 . Each plug-in inlet is provided with a recess  63  on two opposite walls. In addition, each plug-in inlet has two finger-like guide elements  64  and  65  extending in the plug-in direction.  
         [0035]    The individual plug-in connectors  1  have a housing  3 , in which there is arranged an optical end piece  4 . The optical end piece  4  projects at the front side of the housing, is spring-mounted in the plug-in direction in the housing, and is designated as a “ferrule”. The plug-in connector, which overall is of a flat design, has two narrow housing sides with latching arms  6 . Each latching arm  6  has a latching lug  7 . The latching lugs  7  are used to latch the plug-in connector in the recesses  63  of the plug-in inlet  62  of a coupling partner  60 . Each latching arm  6  has a transversely running web  8  and a free, movable end  9  with grip studs.  
         [0036]    One broad flat side of the plug-in connector  1  is provided with a sliding key  5  in the form of a web, which has an interruption  10 . This interruption forms a recess in the surface of the plug-in connector  1 . On the opposite broad face of the housing  3 , the plug-in connector is provided with a plateau  11  for providing guidance into the holder  20 .  
         [0037]    In order to accommodate the plug-in connectors  1  and the plug-in inlets  62  of the coupling partners  60 , the holder  20  has an outer housing  23  and an inner housing  24 . The outer housing  23  is fixed to the housing wall  21  by a U-shaped, open clip  22 . Part of the inner housing  24  is a locking element  25 , which is designed as a two-armed lever and from which the externally accessible free end  52  can be seen.  
         [0038]    According to FIG. 2, when plug-in connector  1  and coupling partner  60  are joined, the respective latching lug  7  of one plug-in connector engages in a corresponding recess  63  in a plug-in inlet  62 . Furthermore, on the finger-like guide element  64  of the plug-in inlet  62 , an operative face  66  can be seen, which is engaged with a wing-like extension  26  on the locking element  25 . The interaction of the guide element  64  with the wing-like extension  26  will be explained in more detail further below.  
         [0039]    Because of the cut-open holder  20 , FIG. 2 clearly shows the two clips  22  formed as a plastic component. Latching tongues  29  belonging to the outer housing  23  engage in corresponding recesses  74  in the clip  22 . The recesses  74  in the clip  22  and the latching tongues  29  are dimensioned such that the outer housing  23  can be displaced within certain limits transversely with respect to the plug-in direction, transversely with respect to the clip  22  and therefore transversely with respect to the housing wall  21 .  
         [0040]    [0040]FIG. 3 shows an enlarged illustration of a plug-in connector  1  with the optical end-piece  4 , which is designed as a ferrule, arranged inside the housing  3  and the latching arms  6 . The latching arms  6  are respectively provided with a latching lug  7  and a web  8  that runs transversely. Both the latching lug  7  and the web  8  have a run-on chamfer. Also marked here is a sliding face  72 , with which the plug-in connector  1  slides along on corresponding faces on the inner housing  24  of the holder  20  (see FIG. 1). Furthermore, at the cable end of the sliding key  5 , a transverse web  12  is arranged which, during the insertion of the plug-in connector  1 , limits the plug-in depth of the plug-in connector  1  by striking a front edge of the inner housing  24 .  
         [0041]    [0041]FIGS. 4 and 5 each show a perspective view of two sectioned halves of the holder  20  including the outer housing  23  and inner housing  24 . The section plane runs in the plug-in direction runs vertically in the view of FIG. 2, and the sectioned half shown in FIG. 4 is folded rearward through 180° as compared with the sectioned half shown in FIG. 5. In both figures, the outer housing  23  is shown only partially. Together with FIGS. 6 and 7, it can be seen here that the outer housing  23  includes a plastic part  27  with a U-shaped cross section and a sheet-metal part  28  with a likewise U-shaped cross section. The sheet-metal part  28  forms a housing wall and is placed in the manner of a clip on the plastic part  27 . The sheet-metal part  28  is in each case provided with a latching tongue  29  on the two U-shaped legs. The tongue engages into a corresponding recess in the clip  22 , as shown in FIG. 2. The sheet-metal part  28  of the outer housing  23  is further provided with a bearing pin  37 , with which a hole  38  on the opposite wall is associated. Pin  37  and hole  38  serve for pivotably mounting the inner housing  24  in the outer housing  23 . The inner housing  24 , which is configured as a plastic part with a box-like outer contour, likewise has a hole  32  and a pin  33  in each case on two opposite walls  30  and  34 . The pin  37  of the outer housing is provided to engage in the hole  32  in the inner housing, and the pin  33  of the inner housing is provided to engage in the hole  38  in the outer housing. The pin  33  of the inner housing reaches through a metal clip which is placed on the inner housing and which has an extension  41  acting as a spring. This spring  41  is engaged with the locking element  25 , as can also be seen in FIGS. 10 and 12.  
         [0042]    The inner housing  24  is arranged with play in the outer housing  23  in such a way that it can be pivoted vertically within certain limits about the axis formed by the pins  37  and  33 .  
         [0043]    The inner housing has a wall  30  with two guide webs  31  running in parallel in order to guide the aforementioned plateau  11  that is on one broad flat side of the plug-in connector  1 . Formed on the opposite wall  34  is a guide part  35 , which serves both to guide the plug-in connector  1  and to guide the plug-in inlet  62  of a coupling partner  60 . Furthermore, two guide webs  36  are provided on this wall to guide the fingerlike guide elements  64  and  65  of a plug-in inlet  62 .  
         [0044]    The guide part  35  substantially includes two webs  48  which are L-shaped in cross section and which have the two legs  49  and  50 . These webs are connected to each other via transverse struts  51 . In each case two legs  50  running parallel to each other and belonging to the two webs  48 , together with the transverse struts  51 , form a groove  44  between them, in which the sliding key  5  of a plug-in connector  1  is guided. The inner faces of the L-shaped webs  48  and the two webs  36  are used to guide and position the finger-like guide elements  64  and  65  of a plug-in inlet  62  and are provided with appropriate run-on chamfers.  
         [0045]    The upper wall  45  and the lower wall  46  of the inner housing  24  are provided, at the end facing the plug-in connectors  1 , with a recess which is configured in such a way that an inclined plane  47  results. When the coupling between the plug-in connector and coupling partner is being released, these inclined planes come into engagement with the transverse webs  8  on the latching arms  6  of the plug-in connectors  1 .  
         [0046]    The pins  33  and  37  and holes  32  and  38 , which are arranged in the inner and outer housing  23 / 24  for pivotably mounting the inner housing  24  in the outer housing  23 , are arranged in relation to the guide webs  36  and guide faces on the guide part running in the inner housing in such a way that the holes and pins are arranged at a slight distance f from the edge of the holder, while the guide webs and guide faces begin at a greater distance g from the corresponding edge of the holder.  
         [0047]    [0047]FIG. 8 is a sectional illustration showing a view of the locking element  25  arranged in the inner housing  24 . The locking element  25  is provided with two bearing pins  33 , which each engage in a recess on a leg  49  of an L-shaped web  48 . As a result, the locking element  25  forms a two-arm lever, whose one end is configured as a locking lug  54 . This end is subject to the action of the leaf spring  41  (see FIG. 7). Branching laterally from the locking lug  54  are two wing-like extensions  26  which run parallel to the pivot axis of the lever and are in each case provided with a run-on chamfer  42 . The extensions  26  serve to unlock the locking element as the result of an action of the finger-like guide elements  64  and  65  of a plugs in inlet  62 . When they come into engagement with the wing-like extensions  26 , the guide elements  64  and  65  lift the locking lug  54  out of the groove formed between the L-shaped webs  48  and therefore out of the recess or interruption  10  in the sliding key  5 . Consequently, the locking element  25  is used to retain a plug-in connector  1  axially in the holder  20  when the coupling partner  60  is not yet plugged in or has been withdrawn. The locking can also be cancelled by the locking element being actuated manually at its free end  52  which is not loaded by a spring.  
         [0048]    [0048]FIG. 8 also clearly shows the hole  32  in the wall  30  and the pin  33  on the opposite wall  34 . It is also possible to see the configuration of an L-shaped web  48  having the transverse struts  51 , and also the configuration of a guide web  36 . Also marked are the sliding faces  55  for the sliding face  72  of the plug-in connector  1  that is provided with the sliding key, the guide face  56  for the sliding key  5  and the sliding face  57  formed by the web  36  for a guide element of the plug-in inlet.  
         [0049]    According to FIG. 9, the plug-in inlet  62  is of substantially box-like shape and is used to accommodate the front end of a plug-in connector  1 , likewise of substantially box-like shape. Two opposite narrow sides of the plug-in inlet  62  are each provided with a recess  63  to accommodate a latching lug  7  of the plug in connector  1 . The recess  63  is dimensioned in the axial direction such that the plug-in connector  1  and the plug-in inlet  62  can be displaced axially in relation to each other within certain limits when in the latched state.  
         [0050]    The two finger-like guide elements  64  and  65  are of flat design and the finger tips thereof are provided with run-on chamfers  69 . Arranged on the upper side of each guide element is a web-like elevation  67 . This elevation  67  is used for mechanically stabilizing the flat guide elements. In addition, part of this elevation  67  begins in a manner set back axially. A chamfer  70  is provided at the start of this set-back part. This chamfer  70  and the adjacent operative faces  66  come into engagement with the wing-like extensions  26  on the locking element  25  when the plug-in inlet is inserted into the holder  20  of the coupling configuration. Further chamfers  71  for the guidance of the guide elements  64  and  65  are provided on the narrow edges of the flat guide elements.  
         [0051]    FIGS.  10  to  13  permit further details of the novel coupling configuration to be seen. Thus, FIG. 10 shows the engagement of the locking element  25  in the recess  10  in the sliding key  5  of the plug-in connector housing  3 . FIG. 10 also permits the assignment of a finger-like guide element  64  having the chamfer  70  to a wing-like extension  26  of the locking element  25  to be seen. When the plug-in inlet and the plug-in connector are joined, the chamfer  70 -lifts up the wing-like extension  26  and therefore guides the locking lug of the locking element out of the recess  10  in the plug-in connector housing  3 . This takes place at an instant at which the latching lugs  7  of the latching arms  6  (see FIG. 11) are latched into the corresponding recesses  63  in the plug-in inlet  62 . In order to ensure that plug-in connector and plug-in inlet latch with each other before the guide element  64  releases the locking element, the distance a of the latching edge  73  of the recess  63  from the inclined faces  70  on the guide elements  64 / 65  have to be chosen to be less than the sum of the distance b of a latching lug  7  from the recess  10  in the sliding key of the plug-in connector and the distance c of the locking lug  54  from the wing-like extensions  26  of the locking element  25 .  
         [0052]    When the coupling configuration is uncoupled by pulling the coupling partners arranged on a circuit board, and therefore the associated plug-in inlets, out of the holders  20  and the plug-in connectors  1  arranged therein, according to FIG. 12, first of all the operative connection between the finger-like guide elements  64  and  65  and the wing-like extensions  26  of the locking element is cancelled, as a result of which the locking lug  54  latches into the corresponding recess  10  in the plug-in connector  1  again. Then, the plug-in connector is also pulled further to the left in the axial direction by the coupling between latching lug  7  and recess  63  in the coupling partner, the transverse webs  8  provided on the latching arms  6  running with their run-on chamfers onto the chamfers  47  in the inner housing  24 . This results in the latching arms  6  being pressed against the plug housing  3  and finally the latching between the latching lugs  7  and the recesses  63  is cancelled. For this purpose, the distance d provided in the plug-in direction of the recess  10  in the sliding key  7  from the web  8  running transversely is greater than the distance e provided in the plug-in direction of the latching lug  54  from the inclined plane provided in the inner housing  24  and forming the run-on chamfer  47 .  
         [0053]    In the coupling configuration illustrated, both plug-in connectors  1  are of identical design and are arranged in mirror-image fashion in relation to each other. Accordingly, the two holders that are each formed of a clip, an outer housing and an inner housing are of identical design and are arranged in mirror-image fashion in relation to each other in an opening in the wall of the housing  3 . The two coupling partners  60  are likewise of identical design and are arranged in mirror-image fashion in relation to each other. One coupling partner is arranged on the upper side and the other on the underside at the edge of the circuit board  72 .