Abstract:
A connector element is configured in a manner of a flat connector and has a two-part connector housing extending in the longitudinal direction and a locking mechanism for forming a lockable plug-in connection with a counterpart. The locking mechanism contains a locking element having a pull tab fastened thereto. In order to enable a reliable emergency release even if the pull tab is ripped off, the locking element is led outside by a mounting part and the pull tab is irremovably fastened to the mounting part by riveting the pull tab or injection molding the pull tab onto the mounting part. This also makes it possible to easily adapt the pull element in a customer-specific manner.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This is a continuation application, under 35 U.S.C. §120, of copending international application No. PCT/EP2012/066455, filed Aug. 23, 2012, which designated the United States; this application also claims the priority, under 35 U.S.C. §119, of German patent application No. DE 10 2011 111 280.8, filed Aug. 26, 2011; and of German patent application No. DE 10 2011 088 124.7, filed Dec. 9, 2011 the prior applications are herewith incorporated by reference in their entireties. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The invention relates to a connector element. 
     The connector element is a so-called flat connector having a locking mechanism, as is used as an electrical or optical connector in particular in computer networks. Such connector elements are also known as small form factor pluggable (SFP) or quad small form factor pluggable (QSFP) and have their geometrical dimensions determined in appropriate standards. International patent disclosure WO 2011/089003 A1 (corresponding to U.S. Pat. No. 8,556,646) discloses such a QSFP connector. Furthermore, international patent disclosure WO 2011/072869 A1 (corresponding to U.S. Pat. No. 8,444,430) discloses an SFP connector element (also referred to as a CXP connector element). 
     The QSFP connector is distinguished, in principle, by an unlocking mechanism which is integrated in the side walls of the housing. Provided for this purpose is an approximately bracket-form locking element which is guided internally, in the rear region of the connector housing, between two housing halves. Accordingly, the locking element has two locking arms, which extend in the longitudinal direction in the side walls and at the ends of which is arranged a respective catch element, which projects laterally beyond the locking arms. 
     In contrast to such QSFP connector types, the catch element in the SFP connector types is formed on an upper side of the connector housing. In the case of the SFP connector according to international patent disclosure WO 2011/072869 A1, the locking element as a whole is configured in the manner of a rocker, on which the catch element is formed in the front end. 
     An actuating element is usually provided to actuate the locking mechanism and, both by pulling or rotating, manually transfers the locking element from a locked position into an unlocked position. The known SFP or QSFP connectors from the two aforementioned documents each have a pull tab which is pulled in the longitudinal direction of the connector for unlocking purposes. 
     As already mentioned, such connectors serve for connecting in particular data cables in computer networks to equipment or else distributors. The amount of installation space here is often restricted and the individual connectors are arranged in a very close-packed manner one beside the other. Internally, the connectors have suitable electronics, usually integrated in a printed circuit board. The printed circuit board with appropriate contacts, at the same time, also forms a contact tab, which has its end side freely accessible at the front end of the connector housing and via which a plug-in contact with the respective component is formed. The connectors are generally configured for repeated unlocking and locking. 
     SUMMARY OF THE INVENTION 
     Proceeding herefrom, it is an object of the invention to configure such a connector element for permanently reliable, reversible locking and unlocking. 
     The connector element has a locking mechanism for forming a lockable plug-in connection to a counterpart. For this purpose, it has a connector housing, which extends in the longitudinal direction and has two housing parts, namely an upper part and a lower part. The connector housing extends from a rear end wall with a cable opening for a cable which is to be connected, to a front end side, with an opening for a plug-in contact element. The connector housing here usually forms a housing step, which separates a rear part from a front connector region, by way of which the connector is plugged into the counterpart (component). The step here is usually formed merely on the upper side, but possibly also on the underside. The plug-in contact element is the already described printed circuit board. 
     The locking mechanism has a longitudinally movable pull tab, which is arranged outside the housing and is connected in a rotationally fixed manner to a locking element arranged, at least in part, within the housing. The locking element, in turn, has a catch element which is intended for the form-fitting unlocking and locking of the connector element in relation to the counterpart. When the pull tab is subjected to pulling action (exclusively) in the longitudinal direction, the catch element can be transferred out of a locking position into an open position. Of particular importance, then, is the fact that the locking mechanism is of two-part configuration, that is to say, on the one hand, the locking element has a rear installation part, by which it is guided out of the housing via the rear end wall, and also has, as second part, the pull tab, which is fastened in a non-releasable manner on the rear installation part. 
     The at least two-part configuration makes it possible, on the one hand, to provide differently configured, client-specific pull tabs for example with client-specific printing or with client-specific designs, with the parts being otherwise identical. A further critical advantage can be seen in the fact that even if the pull tab, which usually consist of plastics material, is torn off, the installation parts arranged outside the housing can still be gripped by a tool in order to effect emergency unlocking of the connector. In the case of a single-piece configuration in particular made of plastics material, that is to say a configuration in which the pull tab and the unlocking element, which extends into the housing, are formed in one piece from a plastics material, there is the problem of tearing off occurring within the housing, in which case there is no possibility of release. The configuration selected here therefore renders emergency unlocking possible. 
     The pull tab here is riveted in particular to the installation part. In an alternative configuration, the pull tab is configured as a plastic part which is molded onto the installation part. For reliable connection, the installation part here preferably has form-fitting elements such as holes, undercuts, etc. The molding also achieves, overall, a very pleasing visual impression. 
     In the case of riveting, the rivets are preferably retained in captive fashion in the pull tab prior to the actual fastening on the installation part, and this makes easy installation possible. 
     The locking element with the installation part is preferably formed from metal and thus in particular from a material with a higher tensile strength than the pull tab made of plastics material. This ensures that, in the event of mechanical overloading, the pull tab tears outside the housing, rather than, for example, the locking element within the housing. 
     The pull tab preferably extends generally over a plane of an outer side of the housing, in which case therefore the pull tab is arranged on one side of the cable, which is fed to the connector via the rear end wall of the latter. According to a first variant, the pull tab here, as seen in a side view, is of approximately L-shaped design at least in the region in the vicinity of the housing and has two lateral vertical arms, which butt against the rear side of the housing and are fastened on corresponding respective installation legs of the installation part. The cable opening is located between the two opposite vertical arms. The vertical arms extend, in particular, over the entire height of the connector housing. A particular advantage of this configuration can be seen in the fact that the pull tab can be fastened optionally at the bottom or top, with the locking element being of identical design in each case. It is therefore generally provided, in a preferred configuration, that the pull tab can be installed in a state in which it is offset by rotation through 180° in relation to the longitudinal direction. According to a first variant, this takes place solely by the pull tab itself being installed differently; in a second variant, the pull tab can be rotated through 180° together with the locking element, no further modifications to the rest of the components of the connector having to be carried out. It is therefore possible in this case (QSFP) for the locking element to be installed together with the pull tab optionally in one orientation or the other (rotated through 180° about the longitudinal direction). 
     The installation part, in addition, preferably has a transverse bracket, on which the pull tab is fastened. The transverse bracket here forms, with the rest of the installation part, a monolithic part, for example a sheet-metal part which is formed by bending. 
     Rivets are used for example to fasten the pull tab on the transverse bracket. In an alternative configuration, the two L-shaped vertical arms are connected to one another via such a transverse bracket, which may also be arranged to run within the housing. 
     Such connector elements generally have very narrow tolerance limits predetermined for the housing dimensions, so that reliable locking is made possible. In order to ensure positionally accurate installation of the two housing parts, which are configured in the manner of two half-shells, a preferred development forms a play-free, step-like connection between the upper part and lower part in the front connector region of the connector housing. For this purpose, the upper part and lower part engage one inside the other to form a step and have, at the same time, corresponding installation slopes, which allow the two parts to pivot in relation to one another for installation purposes. Step-like formation here is understood to mean a form-fitting connection in the vertical direction perpendicular to the longitudinal direction, and therefore the position of the two housing halves in relation to one another is fixed in the vertical direction. The slope, which adjoins the step and is oriented, for example, at an angle between 30° and 60°, especially makes it possible for the two housing parts to be pivoted relative to one another, for installation purposes, about a pivot axis which runs perpendicularly to the longitudinal axis and parallel to a parting plane between the two shell-like housing parts. 
     The one of the two housing parts, in particular the upper part, expediently contains for this purpose, on the end side of each of its side walls, a nose, preferably with a rectangular side surface, which extends parallel to the longitudinal direction and is adjoined by the installation slope. The complementary lower part, accordingly, has a recess with an adjoining installation slope. Appropriate accurately dimensioned production achieves, overall, a play-free snug fit between the two parts. 
     In an expedient development, in particular in addition to the step-like connection, there is likewise a form-fitting connection of the housing parts formed in the rear region, and therefore the housing parts are meshed with one another in the longitudinal direction, so as to prevent horizontal displacement. The form fit thus acts in the longitudinal direction. The two housing parts are brought into the formfitting connection at the rear on account of the pivoting movement. During installation, first of all the upper part is introduced into the recess with the nose in front, and inclined at an angle in relation to the lower part, and is then pivoted in relation to the lower part. The two housing parts here engage one inside the other at the rear end in order to form the meshing. 
     In the case of the configuration as an SFP connector element, the locking element expediently has a rocker which can be tilted about a horizontal axis of rotation and has the catch element at its front end. A second rocking arm is provided in the rear region, behind the axis of rotation, and thus opposite to the catch element, the second rocking arm preferably being inclined obliquely and having the pull tab acting on it by way of a transverse strut in order for the rocker to be actuated. 
     As already explained above, there is a partial risk of the pull tab tearing off and thus of it no longer being possible for the connector to be unlocked. In order to solve this problem, a preferred configuration arranges, on the rocker, an actuating element, which projects beyond the upper side of the housing and is accessible to a tool such that emergency actuation of the rocker is rendered possible when the connector element has been plugged in place. In the simplest case, the tool is a pin-like element which is pushed against the actuating element in the longitudinal direction in order to tilt the rocker about the axis of rotation. 
     The rocker and the catch element are expediently configured such that the catch element, upon actuation of the rocker from a locking position into an unlocking position, is drawn in inward in the direction of a housing center. The catch element is thus drawn away from the counterpart (component) for the unlocking operation. The locking of the connector element usually takes place by way of a cage-like insert in a housing of the components, wherein the catch element here engages in a corresponding recess. In the case of conventional SFP connector variants, as described, for example, also in international patent disclosure WO 2011/072869 A1, the catch element engages in the corresponding recess in the counterpart housing from above and is drawn away upward for the unlocking position. The cage or the counterpart housing element is thus stored on an interim basis between an upper side of the connector housing, in the connector region, and the catch element. Tolerance-related problems in the production of such fastening cages, which are usually configured as parts formed by punching and bending, may result in unlocking-related problems on account of incomplete unlocking. The solution described here does away with this problem. 
     It is also the case, in a preferred configuration, that a spring element is arranged in the front region, the spring element subjecting the front part of the rocker with the catch element to a spring force in the vertical direction. The force is therefore directed perpendicularly to the axis of rotation of the rocker, the force therefore acting, as far as possible, at right angles. The spring element pushes the rocker outward into the locked position. The spring element here is, for example, a leaf spring or else a helical spring. 
     It is also the case that the rocker is preferably mounted in a rotatable manner on a rotary pin. The rocker and the rotary pin are therefore two separate parts which can be rotated relative to one another. This achieves mounting which has as low a level of friction as possible, as a result of which the spring force exerted by the spring element is realized as efficiently as possible for reliable locking. 
     In the case of the SFP connector element, the rocking mechanism is arranged in the rear sub-region of the connector housing. Accordingly, the rear sub-region is usually configured to be of somewhat higher construction. In an expedient configuration, the rear sub-region contains an accommodating chamber for the rocker, the accommodating chamber being closed in relation to the rest of the housing interior. This expediently takes place via a metallic shielding plate, which is fixed, for example riveted, to the housing. In particular also the rear rocking leg is supported on the lower boundary of the accommodating chamber, and this leg is therefore pressed into a defined basic position on account of the spring force which acts on the front region of the rocker. 
     Using the shield element also has particular advantages in terms of EMC, since a desired shielding action is achieved as a result. Fastening the shielding plate separately on the housing, furthermore, isolates the unlocking mechanism, that is to say the rocker function, completely from the rest of the components in the connector housing. 
     In the case of the connector element being configured as a QSFP connector, the locking element contains two longitudinally extending locking arms, which run laterally on, and preferably partially in, the side walls of the connector housing and each have, at the end, a catch element projecting outward perpendicularly to the longitudinal direction. The locking arms here are preferably configured as sheet-metal tabs which are connected to one another in the rear region via a transverse bracket. The transverse bracket is preferably part of the installation part, which is located outside the connector housing and on which the pull tab is fastened. As an alternative to the configuration with the transverse bracket, each of the sheet-metal tabs is guided individually rearward out of the housing and are connected to one another, only via the pull tab, outside the housing. 
     For reliable locking, a preferred configuration fastens a longitudinally extending spring, in particular helical spring, on each of the locking arms. The respective spring is therefore more or less part of the locking arm and is pre-installed on the same, which simplifies installation. Orientation in the longitudinal direction, in addition, achieves effective action of spring force into the basic position. The basic position here is a front position, in which the locking arm is pushed, in relation to the connector housing, in the direction of the front end side. 
     In respect of the captive fastening of the spring on the respective locking arm being of the simplest possible configuration as possible, the locking arms are each preferably configured as parts which are formed by punching and bending and have a punched-out portion with a sheet-metal tab bent out of the same. The spring is fixed on the bent-out sheet-metal tab. The spring is preferably clamped here, and therefore the sheet-metal tab is a clamping tab. The sheet-metal tab expediently contains a plurality of sub-tabs, which form a clamping mount for the spring in the manner of a cage. 
     In order to increase the stability of the connector housing—irrespective of the specific configuration as an SFP or QSFP connector—the one housing part, in particular the upper part, on its front end side, has a transverse bracket, which is angled in the direction of the lower part and also engages in the form-fitting manner around the lower part. This achieves a reliable form-fitting connection in the vertical direction perpendicular to the longitudinal direction. Engagement of the transverse bracket around the lower part achieves, overall, good guidance of the lower part in the upper part. 
     In order for the two housing parts to be connected reliably, the housing parts are also preferably fastened to one another via rivets. For this purpose, a rivet guide is formed within the housing parts, the rivet guide extending through the housing wall and preferably guiding the rivet over its entire length. 
     In order to form a rivet guide which is as accurate and free of play as possible, and at the same time allow easy installation, the rivet guide has the smallest diameter formed at its two opposite ends. The rivet guide, overall, is therefore curved for example convexly in its central region. As an alternative, it is also possible for the rivet guide to taper conically at each of its ends. 
     The above described configuration of the housing parts with the longitudinally form-fitting connections between the two housing parts both in the front and in the rear regions makes it possible for the rivet connection to be reliably relieved of loading in the longitudinal direction, and therefore the rivet connection has to hold the two housing parts together merely in its longitudinal direction, that is to say in the vertical direction (perpendicular to the longitudinal direction of the connector housing). 
     As already mentioned, within the connector housing, the actual connector electronics are fitted, in particular, on a printed circuit board. In a preferred embodiment, the printed circuit board is fixed in a play-free manner, and also clamped, preferably by peripheral protuberances. The protuberances here are arranged opposite one another on a respective housing part. The protuberances preferably are arranged both in the upper part and in the lower part. 
     The sum of features described here forms, overall, a flat connector which is particularly suitable for any emergency unlocking which may be necessary and which, at the same time, displays a reliable mechanical connection between the housing halves and also has an effectively acting locking mechanism, via spring elements, which retain the catch elements in each case reliably and reversibly in the locking positions. 
     The individual aspects described here give rise, in particular in combination, to an advantageous combined effect so as to form a product which is marketable in all respects. A large number of the aspects, however, may also be realized independently of the features characterizing the main claim, that is to say of the two-part design between the pull tab and locking element. This applies, in particular, to the following features, and combinations of features, which are considered to be inventive in their own right without this two-part configuration between the locking element and pull tab. 
     Other features which are considered as characteristic for the invention are set forth in the appended claims. 
     Although the invention is illustrated and described herein as embodied in a connector element, 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. 
     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 SEVERAL VIEWS OF THE DRAWING 
         FIG. 1  is a diagrammatic, perspective view of a QSFP connector element according to the invention; 
         FIG. 2  is a diagrammatic, perspective view of an SFP connector element according to the invention; 
         FIG. 3  is a diagrammatic, perspective view showing two different variants of the fastening of the pull tab, that is to say a molded-on pull tab (left-hand half of  FIG. 3 ) and a riveted-on pull tab (right-hand half of  FIG. 3 ) using the example of the SFP connector element; 
         FIG. 4  is a diagrammatic, perspective view of the SFP connector element in a detail-form, partial elevation in order to explain more specifically the variant shown in  FIG. 3  with the molded-on pull tab; 
         FIG. 5A  is a diagrammatic, perspective view of the QSFP connector element with the pull tab molded on; 
         FIG. 5B  is a detail-formed sectional view of the connector element illustrated in  FIG. 5A , this time in the region of the molded-on pull tab; 
         FIG. 6  is a side view of the SFP connector element in order to explain the step-like play-free connection between the two housing parts, the connecting region being illustrated on an enlarged scale; 
         FIG. 7A  is a diagrammatic, perspective view of a lower part of the housing in the rear region, with a cable opening, in order to illustrate the form-fitting connection between the two housing parts in the manner of meshing in the rear sub-region; 
         FIG. 7B  is a diagrammatic, perspective view of the corresponding upper part of the connector housing; 
         FIG. 8A  is a sectional view of the SFP connector element in order to explain an unlocking mechanism with an emergency unlocking function; 
         FIG. 8B  is a sectional view according to  FIG. 8A  together with a tool in the event of emergency unlocking; 
         FIG. 9  is a perspective view, from an inside, of the upper part of the housing of the SFP connector element with a shielding plate riveted on; 
         FIG. 10  is a perspective view of the lower part of the housing of the QSFP connector element with the locking element inserted and the pull tab fastened thereon, the region of the spring element being illustrated on an enlarged scale; 
         FIG. 11  is a plan view of a wall of the connector illustrated in  FIG. 10 ; 
         FIG. 12A  is an enlarged plan view of the illustration of  FIG. 11  in a region of a catch element at an end of the locking arms in a locking position; 
         FIG. 12B  is a plan view which is comparable to  FIG. 12A , but with the locking arm in an unlocked position; 
         FIG. 13  is a perspective view of one of the locking arms of the QSFP connector element with a spring pre-installed thereon, in captive fashion; 
         FIG. 14A  is an exploded, perspective view of a lower part of the housing and an upper part of the housing in a further variant, in which the upper part of the housing has an angled bracket on its front end side, an angled front region also being illustrated on an enlarged scale; 
         FIG. 14B  is a side view of the connector element illustrated in  FIG. 14A , this time in the installed position, with the front end region being illustrated on an enlarged scale; and 
         FIG. 15  is a sectional view in a region of a fastening rivet for riveting the two housing parts. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In the figures, equivalent parts are provided with the same designations. Referring now to the figures of the drawing in detail and first, particularly, to  FIGS. 1 and 2  thereof, there are shown different types of connector elements  2 A,  2 B, that is to say a QSFP connector element  2 A ( FIG. 1 ) and an SFP connector element  2 B ( FIG. 2 ), each have a two-shell part connector housing  4  with an upper part  4 A and a lower part  4 B. The connector elements  2 A,  2 B extend in a longitudinal direction between a rear end wall  6  and a front end side  8 . A cable opening  10  for a cable which is to be introduced is formed on the rear end wall  6 . The front end side  8  has an opening  12  for a plug-in contact element formed by a printed circuit board  14 . In the rear region, the connector housings  4  each have a housing step  16 , as a result of which the height, but not the width, of the connector is reduced. The front region, which adjoins the housing step  16 , forms a connector region  18 , by which the connector element  2 A,  2 B, in the plugged-in state, is plugged in a corresponding counterpart for contact purposes. The two housing parts  4 A,  4 B are preferably connected exclusively in the rear region via fastening rivets  19 . 
     A respective installation part  20  of a locking element  22 A, B, which runs, at least in part, in the interior of the connector housing  4 , passes out of rear end wall  6 . A pull tab  24  is fastened on the installation part  20 , and can be actuated merely in the longitudinal direction, no rotary movement being possible. 
     The locking element  22 A,  22 B has a respective catch element  26 A,  26 B, which is configured in the manner of a projecting nose. 
     In the case of the QSFP connector element  2 A, the locking element  22 A contains two lateral, longitudinally running locking arms  28 , or is formed thereby, the catch element  26 A being formed at the end of the same. The locking arms  28  are sheet-metal tabs guided in a respective side wall  30  of the connector housing  4 . 
     In contrast to this, the catch element  22 B of the SFP connector element  22 B is arranged on the upper side of the connector housing  4 , in the connector region  18 . In the region of a catch element  26 B, the connector housing  4  is additionally enclosed by an EMI cage for shielding purposes. 
       FIGS. 3 ,  4 ,  5 A and  5 B will be used herein below to describe various possible ways of fastening the pull tab  24 .  FIG. 3  illustrates two basically different variants. The left-hand half of  FIG. 3  shows a variant in which the pull tab  24  has vertical arms  32 , by which it is fastened on corresponding installation legs  34  (see  FIG. 4 ) of the installation part  20 . In the case of the second variant, the pull tab  24  is fastened on a transverse bracket  38 , which forms the projecting installation part  20 , via rivets  36 . 
     Of particular note here is the variant with the molded-on pull tab  24 , in particular with the approximately L-shaped configuration thereof, which is formed by the vertical arms  32  and adjoining, essentially longitudinally extending lateral arms, which engage around a gripping chamber. In the rear region, a marking panel, for example for applying a brand name, is formed between the lateral arms. The particular advantage of this approximately L-shaped configuration in conjunction with the molding possibility can be seen in the fact that client-specific production can take place and the pull tab  24  can be readily arranged above or also beneath a cable which is to be introduced. Rotation through 180° is rendered possible in this respect. 
     In the case of SFP variant ( FIG. 4 ), the installation part is formed, internally, approximately as a U-shaped bracket, with the installation legs extending in the vertical direction on the outside. The bracket of the insulation part  20  here forms a transverse strut  40 , which can be used to actuate a rocker  42 , which has the catch element  26 B. The transverse strut  40  here is oriented in the transverse direction transverse to the longitudinal direction and also transverse to the vertical direction, in which, for example, the installation legs  34  extend. 
     The longitudinal direction is generally the direction of extent from the rear end wall  6  to the front end side  8 , the transverse direction is the direction of extent perpendicular thereto, from the left-hand to the right-hand side wall  30  (width), and the vertical direction is the direction of extent perpendicular to the longitudinal direction and the transverse direction, from the underside of the housing to the upper side of the housing (height). 
     For form-fitting fastening of the molded-on pull tab  24 , the insulation part  20  has, for example, undercuts, openings etc. in the molded-on region, as can be gathered from  FIG. 4  or also from  FIG. 5B . 
     The next thing, then, is to use  FIG. 6  to explain more specifically the aspect of the step-like, play-free connection between the two housing parts  4 A,  4 B. The upper part  4 A, on the front end of each of its opposite side walls, has a nose  44 , which extends (horizontally) in the longitudinal direction and is adjoined at an obtuse angle, in the direction of the upper side of the housing, by an installation slope  46 . Correspondingly, the lower part  4 B of the housing is provided with a recess  48 , in which the nose  44  engages. An installation slope  46  is likewise formed on the lower part  4 B. The two housings parts  4 A,  4 B are located in the play-free manner one inside the other in this front region, and a snug fit is therefore formed. The two housing parts are thus fastened on one another in a play-free manner in the vertical direction. 
     In order also to achieve a play-free fit with the two housing parts  4 A,  4 B in the horizontal direction, that is to say in the longitudinal direction, a longitudinally acting form-fitting connection is also formed, in addition, in the rear region of the two housing parts  4 A,  4 B ( FIGS. 7A and 7B ). For this purpose, set-back housing portions  50  are provided on the housing parts  4 A,  4 B in order to form a kind of meshing. In particular in combination with the step-like configuration, as is illustrated in  FIG. 6 , this makes it possible for the two housing parts  4 A,  4 B to be fastened reliably on one another. Installation here takes place such that in the first instance the upper housing part  4 A is plugged at least in part, with the nose  44  in front, into the corresponding recess  48 , to be precise it is oriented obliquely in relation to the longitudinal direction and then pivoted in until the set-back housing portions  50  engage one inside the other in the rear region. The meshing in the rear region therefore means that it is not possible for the two housing parts  4 A,  4 B to be displaced parallel in the longitudinal direction for installation purposes. Rather, pivoting is necessary. 
     The next thing, then, is to use  FIGS. 8A and 8B  to explain the aspect of emergency unlocking in the case of the SFP connector element  2 A and also the functioning of the locking element  22 B. 
     As has already been described in relation to  FIG. 4 , the locking element  22 B has the rocker  42 , which is mounted on a rotary pin  43 . The catch element  26 B is formed on the front end region of the rocker  42 . The front end of the rocker  42 , furthermore, is pushed upward into a basic position by a spring element  52 . This basic position corresponds to a locking position. In the rear region, the rocker  42  has a rear rocker arm  54 , which, at least on its underside, has an actuating slope, with which the transverse strut  40  of the installation part  20  is in contact. The rear rocker arm  54  is supported in the downward direction on a shielding plate  56  which, together with the housing-part regions, bounds, and closes off, an accommodating chamber  58  in the downward direction. The shielding plate  56  serves, in particular, also for EMC shielding and is also illustrated in  FIG. 9 . It is riveted to the upper part  4 B of the housing. 
     With the aid of the pull tab  24 , the locking element  22 B is transferred out of the basic position (locked position), which is illustrated in  FIG. 8A , into the unlocked position, which is illustrated in  FIG. 8B . For this purpose, the pull tab  24  is pulled longitudinally in the rearward direction, and therefore the transverse strut  40  slides along the slope of the rocker arm  54  and thus generates the rocking movement, in which case the front rocker arm with the catch element  26 B is pushed downward counter to the spring force. 
     The rocker  42 , as a special feature, has an actuating element  60  formed in the manner of a transverse crosspiece for emergency actuation with the aid of a tool  62 . The actuating element  60  is formed on the rocker  42  and extends beyond the upper side of the housing, in which case it is freely accessible from the outside. The rocker  42  can be transferred into the unlocked position by being pushed forward. 
       FIGS. 10 to 13  will now be used to explain the function of the QSFP connector element  2 A and the special aspect of spring  64 , which is retained in captive fashion. 
     The lateral locking arms  28  are guided inside the rear region of the side walls  30  of the housing, the housing itself forming a guide here. As is illustrated in  FIG. 10 , in the rear region, a spring  64 , configured in the form of a helical spring, is fastened in captive fashion on a respective locking arm  28 . The spring  64  here extends in the longitudinal direction and presses the locking arms into a basic position, as is also illustrated, in particular, in  FIG. 12A . In the front region, the locking arms  28  are each angled some way inward. The catch elements  26 B are arranged, on the outside, in the angled sub-region. In a manner corresponding to the angled portion, it is also the case that a wall region of the housing  4  is configured to slope. In order to lock the connector, a catch tab of the counterpart engages, in a manner which is not illustrated specifically here, in the side wall  30 . For unlocking purposes, the catch tab is pushed away laterally outward with the aid of the catch element  26 A, in which case the connector element  2 A can be drawn out. This takes place by virtue of the pull tab being subjected to pulling action, in which case the locking arm  28  is pulled in the rearward direction, as is illustrated in  FIG. 12B . The catch element  26 A here is pushed laterally outward by the sloping wall region and thus unlocks the catch tab. 
     In order for the spring  64  to be retained in captive fashion, a sheet-metal tab  66  is punched out of the locking arm  28  and bent over. As can be seen from  FIG. 13 , the locking arm  28 , for this purpose, has an approximately T-shaped punched-out portion  68  and the sheet-metal tab  66  contains three sub-tabs, each bent over approximately through 90° to form a cage-like clamping mount, in which the spring  64  is accommodated. 
     A further aspect can be gathered from  FIG. 10 . The printed circuit board  14  accommodated in the connector housing  4  in the definitively installed state (see for example,  FIG. 1 ) is preferably retained in the connector housing  4  exclusively with clamping action by way of protuberances  69  preferably formed on the periphery with both housing parts  4 A,  4 B. The protuberances  69  are formed preferably on the periphery of a respective housing base of the upper part  4 A and lower part  4 B. They are thus expediently formed both in the upper part  4 A and in the lower part  4 B, and therefore the printed circuit board  14  is preferably clamped on the housing parts  4 A,  4 B by the protuberances  65  in a play-free manner both in the transverse direction and in the vertical direction. 
       FIGS. 14A and 14B  will now be used to explain more specifically a further variant for connecting the two housing parts  4 A,  4 B. The upper part  4 A, on its front end side  8 , has a transverse bracket  70 , which is angled approximately vertically downward. The transverse bracket is connected to an upper side of the housing via two lateral vertical arms and lateral horizontal arms adjoining the same. This design creates an end opening, through which the printed circuit board  14  can project on the end side. The upper part  4 A uses the transverse bracket  70  to engage behind a corresponding transverse tab  72  of the lower part  4 B. The mutually corresponding abutment surfaces of the transverse bracket  70  on the transverse tab at the end of the lower part  4 B slope in relation to the horizontal, in order to make easy installation possible. As can be gathered, in particular, from  FIG. 14B , a horizontally running nosepiece is formed at the end of the slope of the transverse bracket  70 , and the nosepiece fits on a shoulder on the transverse tab  72 . The slope means that the two housing parts  4 A,  4 B are retained on one another in a play-free manner. 
     As already illustrated in  FIGS. 1 and 2 , the two housing parts  4 A,  4 B are preferably fastened on one another exclusively in the rear region by two fastening rivets  19 , which extend in the vertical direction through the two housing parts. With the exception of the form-fitting housing connections, there are no further rivet fastenings or other fastening means provided in the front connector region  18 . In order to form a rivet connection which is as reliable and free of play as possible, the two housing parts  4 A,  4 B have formed in them aligned through-passages for the formation of a rivet guide  74 . The latter is provided with a larger diameter in the center region than at its opposite ends. It thus has its smallest diameter at its two opposite ends, that is to say at the entry or exit openings on the housing. The fastening rivet  19  is retained in a play-free manner at said entry or exit openings. The widening in the center at the same time makes easy introduction possible.