Electrical connector keying system

Abstract: A keying system for an electrical connector arrangement includes a connector plug (18) having a housing (88) with a plurality of keying grooves (90) on at least one side thereof. A face plate (86) is mounted on the housing and includes at least one keying notch (92) in alignment with a respective one of the keying grooves (90). The other of the keying grooves are blocked by the face plate (86). A receptacle (26) is provided for receiving the connector plug (18). The receptacle includes a keying protrusion (48) for extending into the keying notch (92) and the respective one of the keying grooves (90). Therefore, the face plate (86) can be interchanged without changing the housing (88) to accommodate different arrays of keying protrusions (48) on the receptacle.

Description: This invention generally relates to the art of electrical connectors and, particularly, to an electrical connector keying system according to the preamble of claim 1. Background of the Invention A shielded electrical connector assembly is known from EP-A-0,624,928 which has the features of the preamble to claim 1. A cable connector is shown including an outer shielding housing having a pair of grooves each on the top and bottom sides of the connector body. The grooves in the pairs have different distances, and these distances correspond to the distances between pairs of grounding ribs in a conductive housing which defines receptacle means. The grooves and the ribs form a polarizing feature for the cable connector which therefore can be inserted into the receptacle means only in one orientation. Electrical connector assemblies often are provided with keying systems to ensure that a given connector can only be mated with its proper mating connector or other connecting device in a desired signal transmission scheme. For instance, a keying system may require that a given plug connector be inserted only into a particular receptacle, while preventing other plug connectors from being inserted into that receptacle. Such keying systems are akin to polarizing systems which require one connector to be mated in only a given orientation to ensure that mating terminals are properly engaged. Such keying systems often include selected arrays of keying protrusions movable into keying recesses only if the array or arrangement of keying protrusions match the arrangement of keying recesses. One of the problems with any such keying system is the expenses involved. In other words, it can be understood that if any given electrical connector or connector plug can be mated with only a keyed complementary connector or connector receptacle, the two connectors in the assembly must be "customized" to a particular keying arrangement. If other connectors are prevented from being "mismated", the other connectors also must be customized or manufactured with different keying arrangements. This continuing change to prevent improper mating involves considerable manufacturing and inventory costs. A connector keying system is known from US-A-4,832,625. The plug housing molded of thermoplastic resin contains a plurality of keying projections extending outwardly and being connected to the housing through flexible hinges and frangible webs. Similarly, the receptacle housing is molded of thermoplastic material and includes key-receiving grooves which have respective latent blocking members assigned thereto. By breaking the frangible webs, the keying projections of the plug can be deflected and made ineffective. Similarly, by breaking frangible webs of a respective latent blocking member this blocking member can be moved into the respective groove and block same. In this manner, different configurations of projections and grooves can be established so that only selected pairs of plugs and receptacles can be mated with one another whereas others are excluded. See also as an exemple document EP-A-0 595 304. Summary of the Invention An object, therefore, of the invention is to provide a new and improved keying system in an electrical connector arrangement. The invention is defined in claim 1. The present invention is directed to solving these problems in a unique system which greatly reduces the costs of manufacture. For instance, the invention is disclosed in a cable or connector plug which includes a housing that can be standard for all connectors, with only a face plate of the housing having to be changed to change the keying system. In addition, the keying system is disclosed in a shielded transmission system which includes a stamped and formed conductive receptacle having a plurality of unbent keying tabs which simply can be bent to achieve a plurality of different keying arrangements. Alternatively, prebent tabs can be cut also to achieve different keying configurations. In the exemplary embodiment of the invention, the keying system is disclosed in a grounding shroud assembly for receiving a cable plug. The cable plug includes a housing having at least one keying recess at a selected location on a side thereof. A grounding shroud assembly includes a conductive frame having a base and at least a pair of sidewalls extending from the base and defining a receptacle for receiving the cable plug. At least one of the sidewalls has at least one keying protrusion for extending into the keying recess. A conductive spring is disposed about the conductive frame and the at least one of the sidewalls. As disclosed herein, the frame is stamped and formed of metal material, and the keying protrusion comprises a tab bent inwardly of the at least one sidewall. The sidewall includes a plurality of stamped unbent tabs, whereby any one or more of the tabs can be bent inwardly to form one or more of the keying protrusions. In the grounding shroud assembly, the conductive spring is generally U-shaped, and the conductive frame is generally U-shaped and nested within the U-shaped spring. The invention contemplates a unique system wherein the housing of the cable plug includes a plurality of keying grooves on at least one side thereof. A face plate is mounted on the housing and includes at least one notch in alignment with a respective one of the keying grooves to define the keying recess. Other of the keying grooves in the housing are blocked by the face plate. Therefore, the face plate can be interchanged without changing the entire housing, to accommodate different arrays of keying protrusions. This saves considerable manufacturing and inventory costs. It should be understood that the novel concepts of the invention are not limited to a grounding shroud assembly for receiving a cable plug. The invention is equally applicable for a wide range of electrical connector arrangements or systems. Other objects, features and advantages of the invention will be apparent from the following detailed description taken in connection with the accompanying drawings, in which like reference numerals identify like elements in the figures and in which: FIGURE 1 is an end elevational view of the grounding shroud assembly of the invention in an exploded view in conjunction with, from top-to-bottom, a cable plug, a panel and a printed circuit board with contact pins; FIGURE 2 is a view similar to that of Figure 1, with the grounding shroud assembly mounted in the panel and connected to the printed circuit board, and with the cable plug about to be inserted into the grounding shroud assembly; FIGURE 3 is an exploded perspective view of the frame and a pair of the springs of the assembly; FIGURE 4 is a perspective view of the frame; FIGURE 5 is a perspective view of one of the springs; FIGURE 6 is a perspective view of the springs mounted on the frame; FIGURE 6A is a fragmented elevational view of three contact pins projecting through apertures in the spring and the frame; FIGURE 6B is a fragmented top plan view looking downwardly on the arrangement of Figure 6A; FIGURE 7 is a view similar to that of Figure 6, with the divider plate of the assembly about to be mounted thereon; FIGURE 8 is a perspective view of the completed assembly mounted in the opening in the panel and on the printed circuit board; FIGURE 9 is a perspective view of the mating end of the cable plug; FIGURES 9A and 9B are fragmented perspective views of the mating ends of two cable plugs having different keying arrangements; and FIGURE 10 is a plan view showing two cable plugs with the keying arrangements of Figures 9A and 9B inserted into a grounding shroud assembly with a similar keying setup. Detailed Description of the Preferred Embodiment Referring to the drawings in greater detail, and first to Figure 1, the invention is embodied in a grounding shroud assembly, generally designated 12. The assembly is shown in Figure 1 for mounting in an opening 14 in a panel 16 and for receiving a cable plug, generally designated 18, on one side of the panel and contact pins 20 from a printed circuit board 22 on the opposite side of the panel. Figure 2 shows grounding shroud assembly 12 mounted in opening 14 in panel 16. The assembly also is shown in Figure 2 mounted on printed circuit board 22 with contact pins 20 projecting into the shroud assembly. Cable plug 18 is insertable into the shroud assembly in the direction of arrow "A". At this point, it should be understood that printed circuit board 22 is of a generally conventional configuration, with conventional contact pins 20 projecting therefrom. Panel 16 is fabricated of conductive material and is part of a shielding casing for protecting components, such as electrical components on the printed circuit board, against electrical emissions and radiations. Except for its keying system, described hereinafter, cable plug 18 also is of a conventional construction with an outer shield and mounts a plurality of female terminals for receiving contact pins 20. The female terminals are terminated to conductors within shielded or coaxial cables 24. Referring to Figure 3, grounding shroud assembly 12 includes two main components, namely a frame, generally designated 26, and one or more springs, generally designated 28. The shroud assembly shown herein is designed for receiving a pair of cable plugs and, therefore, a divider plate (described hereinafter) is used to divide frame 26 into two distinct receptacles for the two plugs. Correspondingly, two separate springs 28 are employed. Referring to Figure 4 in conjunction with Figure 3, frame 26 of grounding shroud assembly 12 is generally U-shaped and includes a base or bottom wall 30 and a pair of sidewalls 32 extending upwardly from the base. The frame is stamped and formed of conductive sheet metal material, such as brass, and base 30 and sidewalls 32 define a receptacle therebetween for receiving one or more of the cable plugs 18. Frame 26 also includes a plurality of apertures 34, 36 and 38 therethrough for receiving contact pins 20 from printed circuit board 22. Apertures 34 are generally rectangular and freely receive ground pins from the printed circuit board. Apertures 36 are circular and also freely receive ground pins from the printed circuit board. Apertures 38 are circular and larger than apertures 36 and receive signal contact pins from the printed circuit board. Frame 26 further includes slots 40 in sidewalls 32, along with notches 42 in the upper edges of the sidewalls. The slots and notches are provided for mounting a conductive divider plate, as described hereinafter. Tabs 44 project longitudinally outwardly from opposite ends of sidewalls 32, and base 30 includes notches 46 at opposite ends thereof. Tabs 44 are provided for mounting conductive end plates, as described hereinafter. Notches 46 facilitate mounting springs 28. Lastly, a plurality of keying tabs 48 are formed out of sidewalls 32 and are bent inwardly of the frame. Unbent keying tabs 48a also are shown in Figures 3 and 4. The keying tabs operate with keying means on cable plugs 18, as described hereinafter. Referring to Figure 5 in conjunction with Figure 3, each spring 28 is stamped and formed of conductive spring metal, such as beryllium copper, and includes a base 50 and a pair of upstanding sidewalls 52 extending from the base for embracing the generally U-shaped frame 26. Sidewalls 52 have protrusions in the form of integral outwardly bowed portions 52a for engaging inner edges of opening 14 in panel 16 to mount the grounding shroud assembly in the panel as shown in Figure 2. The spring also includes integral, inwardly bowed portions 52b which extend around and into the inside of sidewalls 32 of frame 26 for frictionally and electrically engaging the outer shield of the cable plug 18. Each spring 28 of grounding shroud assembly 12 includes a plurality of apertures 54, 56 and 58 through base 50 of the spring. Apertures 54 are H-shaped to define a pair of opposing tabs 54a which deform and grip the ground contact pins which extend therethrough. This functions to mount the grounding shroud assembly onto printed circuit board 22 as shown in Figure 2. Apertures 56 are circular and freely receive the remainder of the ground pins from the printed circuit board. All of the apertures for receiving the ground pins are not H-shaped in order to avoid excessive mounting forces. Apertures 58 freely receive the signal contact pins from the printed circuit board. H-shaped apertures 54 in base 50 of spring 28 register with rectangular apertures 34 in base 30 of frame 26; smaller round apertures 56 in the spring(s) register with smaller round apertures 36 in the frame and larger round apertures 58 in the spring register with larger round apertures 38 in the frame. Lastly, a tab 60 projects outwardly from base 50 at the end of each spring 28, for purposes to be described hereinafter. U-shaped conductive springs 28 are mounted on U-shaped conductive frame 26 by sliding the springs onto opposite ends of the frame in the direction of arrows "B" in Figure 3. Figure 6 shows the two springs fully mounted on and embracing the frame. Once in their fully mounted positions, tabs 60 at the ends of bases 50 of the springs are bent into notches 46 in base 30 of the frame. Figures 6A and 6B show contact pins from the printed circuit board inserted into the apertures in the base of the spring and the base of frame of grounding shroud assembly 12. More particularly, contact pin 20A in Figures 6A and 6B designates a ground pin inserted through H-shaped aperture 54 in the spring and through rectangular aperture 34 in the frame. Opposing tabs 54a grip the ground pin to effectively mount the grounding shroud assembly onto the printed circuit board. Contact pin 20B in Figures 6A and 6B represents another ground pin from the printed circuit board which extends freely through small round aperture 56 in the spring and small round aperture 36 in the frame. Contact pin 20C in Figures 6A and 6B represents a signal pin from the printed circuit board extending freely through larger round aperture 58 in the spring and larger round aperture 38 in the frame. The signal pins pass through larger apertures which are adapted to the impedance characteristics to be achieved with the connector arrangement. Referring to Figure 7, a divider plate, generally designated 66, is shown to include a generally planar body 68 having a pair of mounting legs 70 projecting downwardly therefrom. A pair of arms 72 are spaced outwardly from opposite edges of the body to define grooves 74. The arms terminate in outwardly projecting stop flanges 76. The divider plate is stamped from conductive sheet metal material approximately the same thickness as the sheet metal material of frame 26. Divider plate 66 is mounted onto frame 26 in the direction of arrow "C" (Fig. 7) until the divider plate assumes a position shown in Figure 8, dividing the frame into two distinct receptacles for a pair of cable plugs 18. As the divider plate is mounted onto the frame, sidewalls 32 of the frame move into grooves 74 inside arms 72 of the divider plate, until the bottoms of the grooves seat into notches 42 at the tops of the sidewalls of the frame. Mounting legs 70 at the bottom of the divider plate extend into mounting holes 78 (Fig. 8) in printed circuit board 22. Figure 8 also shows that a pair of end plates, generally designated 80, are used to close the ends of the grounding shroud assembly. End plates 80 are of substantially identical construction to divider plate 66 and, accordingly, like reference numerals have been applied to like portions of the end plates corresponding to the same portions of the divider plate. It can be seen in Figure 8 that the end plates are mounted at the opposite ends of frame 26, with tabs 44 at the opposite ends of sidewalls 32 of the frame press fit into grooves 74 inside arms 72 of the end plates. Mounting legs 70 of the end plates project into mounting holes 78 in printed circuit board 22. After grounding shroud assembly 12 is mounted onto printed circuit board 22 as shown in Figure 8, this subassembly is mounted in opening 14 in panel 16, with the panel abutting against stop flanges 76 of divider plate 66 and end plates 80. With frame 26 being fabricated of a thicker more robust material, such as brass or the like, the frame provides a sturdy structure forming the receptacles for receiving the cable plugs. Springs 28 being fabricated of a thinner springy material, such as beryllium copper or the like, provides a yielding structure for mounting in the panel opening, as well as gripping the plugs and the contact pins in H-shaped apertures 54. Moreover, the unbreached surface of the springs 28 provides shielding against emissions and radiations which the openings provided by the keying tabs 48, 48a may otherwise permit to pass. Figure 9 shows cable plug 18 to include a mating end face 82 having a plurality of passages 84 for receiving contact pins 20 from printed circuit board 22. The passages lead to a plurality of female terminals or contacts within the cable plug and which mate with the contact pins. Mating face 82 is defined by a face 86 mounted on a dielectric housing 88 of the cable plug. Grounding shroud assembly 12 described above in relation to Figures 1-8 and cable plugs 18 include a unique keying system to prevent any given cable plug from being inserted into a wrong receptacle or side of grounding shroud assembly 12. More particularly, Figure 10 shows that opposite sides of housing 88 of the cable plug is provided with a plurality of keying grooves 90. Face plate 86 is provided with a plurality of keying notches 92. The keying notches align with selected ones of keying grooves 90. For instance, in Figure 9, keying grooves 92 at the top of face plate 86 are aligned with the outermost keying grooves 80 of the housing. However, keying notches 92 at the bottom of face plate 86 are aligned with the first and third keying grooves at the bottom of the housing, as looking from the left in the depiction. Therefore, the top of the cable plug may be keyed differently from the bottom of the cable plug. Turning to Figures 9A and 9B, it can be seen that the keying arrangement at the top of the cable plugs shown therein are the same as the keying arrangement at the top of the cable plug in Figure 9. In other words, keying notches 92 in face plates 86 are open to the two outermost keying grooves 90 in plug housing 88. The center two keying grooves 90 at the top of the housing are blocked by face plate 86. However, looking at the bottom of the cable plugs shown in Figures 9A and 9B, it can be seen that face plate 86 in Figure 9A is provided with two keying notches at the right-hand end thereof, and face plate 86 in Figure 9B is provided with two keying notches 92 at the left-hand end thereof. Therefore, the cable plug shown in Figure 9A is keyed different from the cable plug shown in Figure 9B. Now, turning to Figure 10, it can be seen that keying tabs 48 have been bent inwardly from sidewalls 32 of frame 26 to match the keying notches 92 in face plates 86 of the cable plugs. In other words, the cable plug shown in Figure 9A is insertable into grounding shroud assembly 12 at the top of Figure 10, and the cable plug shown in Figure 9B is insertable into the bottom of the grounding shroud assembly in Figure 10. The two cable plugs cannot be interchanged in the respective receptacles on opposite sides of divider plate 66 because of this keying arrangement. It is readily apparent that by providing plug housing 88 with a plurality of keying grooves 90 as shown in Figure 9, only some or all of the keying grooves can be exposed for receiving keying tabs 48 of the shroud assembly, simply by changing face plate 86 and its respective, selected arrangement of keying notches 92. Therefore, the entire plug housing does not have to be changed to change the keying arrangement. Only the face plate 86, with a selected arrangement of keying notches 92, must be changed to change the keying system. Similarly, keying tabs 48 in the sidewalls 32 of frame 26 easily are bent inwardly or cut at selected locations corresponding to the locations of the keying notches in the respective cable plug. The keying tabs 48 can be cut with a small cutting tool even when the spring 28 is already in position and preventing access to the exterior of the frame 26. It will be understood that the invention may be embodied in other specific forms without departing from the scope as defined in the appended claims.

Claims: A keying system for enabling to mate a cable plug (18) only with appropriate receptacle means, comprising the cable plug (18) including a housing (88) having at least one keying recess (90, 92) at a selected location on a side thereof; and the receptacle means for receiving the cable plug (18) including at least a pair of sidewalls (32) and an array of keying protrusions which are adapted to cooperate with the at least one keying recess, characterized in that the keying protrusions comprise foldable metallic tabs (48) on at least one of the sidewalls, at least one of the keying tabs (48) being bent inwardly to match the keying recess (90, 92) of the plug in order to protrude into the path of said keying recess when the cable plug is inserted into the receptacle means. The keying system of claim 1 wherein said receptacle means is a grounding shroud assembly (12) including a conductive frame (26) having a base (30) and said pair of sidewalls (32). The keying system of claim 1 or 2 wherein said cable plug (18) and said receptacle means belong to an electrical connector arrangement, said housing (88) of said cable plug (18) having a face plate (86) mounted thereon and including at least one keying notch (92) in alignment with a respective keying groove (90) on the cable plug (18) so as to form said keying recess, whereby the face plate (86) can be interchanged without changing the housing (88) to accommodate different arrays of keying tabs (48) on the receptacle means. The keying system of any of claims 2 or 3 including a conductive spring (28) about the conductive frame (26) and at least said one of the sidewalls (32). The keying system of any of claims 1 to 4 wherein said frame (26) is stamped and formed of metal material. The keying system of any of claims 2 to 5 wherein said frame (26) is generally U-shaped. The keying system of claim 6 wherein said conductive spring (28) is generally U-shaped, and said conductive frame (26) is nested within the generally U-shaped spring. The keying system of any of claims 5 to 7 wherein said at least one of the sidewalls (32) of the frame (26) includes a plurality of stamped unbent tabs (48a) adapted to be bent inwardly in a desired pattern to form one or more of said keying protrusions. The keying system of any of claims 1 to 8 wherein said housing (88) includes a plurality of keying grooves (90) on at least one side thereof. The keying system of any of claims 1 to 8 wherein said housing (88) has a plurality of keying grooves (90) on opposite sides thereof. The keying system of claims 3 and 9 or 10 wherein a plurality of said face plates (86) is provided, each including at least one notch (92) in alignment with a respective one of a plurality of the keying grooves (90), the face plate (86) being such as to b lock all other keying grooves (90) except for those in alignment with a selected notch (92), the plurality of face plates (86) offering different distributions of the notches (92) to accommodate a selected one of .the different arrays of keying tabs (48) on the receptacle means, a selected one of the face plates (86) being mounted on the housing (88) of the cable plug (18). The keying system of any of claims 2 to 11 wherein the grounding shroud assembly (12) is adapted for mounting in an opening (14) in a panel (16) and for receiving the cable plug (18) on one side of the panel and contact pins (20) from a printed circuit board (22) on an opposite side of the panel, wherein the base of the frame (26) has apertures (34,36,38) therethrough for receiving the contact pins (20), the shroud comprising a generally U-shaped conductive spring (28) including a base (50) and at least a pair of sidewalls (52) extending from the base for embracing the generally U-shaped frame (26) and facilitating mounting the shroud assembly (12) in the opening (14) in the panel (16), the base of the spring having apertures (54,56,58) in registry with the apertures in the base of the frame for receiving the contact pins.

Inventors: DE VRIES KAREL REINIER, DECHELETTE HELEN, DE VRIES, KAREL REINIER, DECHELETTE, HELEN
Applicants: MOLEX INC, MOLEX INCORPORATED
Application year: 1996
Main classification: H01R13
IPC codes: H01R12, H01R13