Abstract:
A coaxial cable connection device comprises a compartment for direct insertion of a previously partially bared end of a coaxial cable to be connected. A contact blade in this compartment is elongate in the same direction as the compartment and spears the coaxial cable between its outer jacket and its shield. The device further comprises a contact terminal with which the central core of the coaxial cable is engaged, a base of which the contact blade is part, and a cap fixed to the base in a closed position of the device and comprising a retaining member in the immediate vicinity of the contact blade in the closed position. The retaining member, in the closed position, grips the outer insulative jacket of a cable speared on the blade on the side opposite the blade.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention relates to coaxial cable connection devices. 
   2. Description of the Prior Art 
   This kind of device must hold the coaxial cable properly and, separately, make a first electrical contact with the metallic braid usually constituting the internal shield of the coaxial cable and a second electrical contact with its conductive central core. This is known in the art. 
   French patent application 2 787 936 discloses a connection device of the above kind comprising a compartment adapted for direct insertion of a previously partially bared end of a coaxial cable to be connected, a contact blade in said compartment elongate in the same direction as said compartment and adapted to spear said coaxial cable between an outer jacket thereof and a shield thereof, a cam rotating about a rotation axis oriented parallel to the direction of the compartment, which cam carries a projecting clamping rib with a tip at a varying distance from the cam rotation axis, and a contact terminal with which the central core of the coaxial cable is adapted to be engaged. 
   With a connection device of the above kind, only the central core of the coaxial cable is bared. In contrast to more conventional connection devices, there is no need to bare the braid to the rear of the bared portion of the central core, which is relatively difficult because it involves removing only the outer jacket. 
   Once the cable, bared in the above manner, is speared on the contact blade, the cable is locked by turning the cam by one quarter-turn using a screwdriver. The clamping rib on the cam then presses against the insulative outer jacket of the coaxial cable to grip the jacket between the clamping rib and the contact blade, which is sufficient to retain the coaxial cable properly. 
   The invention aims to improve this kind of device, in particular with regard to its conditions of use. 
   SUMMARY OF THE INVENTION 
   To this end it proposes a coaxial cable connection device comprising a compartment adapted for direct insertion of a previously partially bared end of a coaxial cable to be connected, a contact blade in the compartment elongate in the same direction as the compartment and adapted to spear the coaxial cable between an outer jacket thereof and a shield thereof, a contact terminal with which the central core of the coaxial cable is adapted to be engaged, a base of which the contact blade is part, and a cap adapted to be fixed to the base in a closed position of the device and comprising a retaining member in the immediate vicinity of the contact blade in the closed position, which retaining member is adapted, in the closed position, to grip the outer insulative jacket of a cable speared on the blade on the side opposite the blade. 
   As in the prior art device mentioned above, there is no need to bare the shielding braid of the coaxial cable before insertion into the compartment, which is effected with the connection device open, of course, with the retaining member or members offset from the contact blade. 
   Thereafter, merely closing the device locks the cable therein thanks to the retaining member or members of the cap gripping the insulative outer jacket. 
   Thus connecting a coaxial cable to a connection device according to the invention is particularly simple and convenient. 
   Furthermore, the provision of one or more retaining members directly on the cap means that the connection device according to the invention may be manufactured from a small number of components and/or be particularly compact. 
   According to features that are preferred for reasons of simplicity and convenience:
         the retaining member is a claw having a pointed end; and/or   the device further comprises two retaining members each formed by a claw having a pointed end; and where applicable   the two claws are centered in a longitudinal plane of symmetry of the cap; and/or   the contact blade has a flat facing each claw; and where applicable   the flat comprises a central V-shaped profile groove.       

   According to other features that are preferred for the same reasons:
         the retaining member is a lug having a sharp edge oriented, in the closed position, in a direction transverse to the direction of the compartment; and/or   the device comprises two retaining members each formed by a lug having a sharp edge oriented, in the closed position, in a direction transverse to the direction of the compartment, the two lugs being situated on respective opposite sides of the contact blade in the closed position; and/or   the device comprises four retaining members respectively formed by two claws having a pointed end centered in a longitudinal plane of symmetry of said cap and two lugs each having a sharp edge oriented, in said closed position, in a direction transverse to the direction of said compartment; and where applicable   each lug has two sharp edges disposed at a distance from each other.       

   According to other features that are preferred for the same reasons:
         the compartment is delimited by a cage comprising a cradle and a first arch and a second arch offset from each other; and where applicable   the contact blade has the general shape of a fingernail whose concave side faces the cradle and whose convex side faces the first and second arches; and/or   the cradle and the first arch delimit an entry mouth into the compartment; and where applicable   the second arch carries the contact blade; and where applicable   the contact blade is attached to the second arch by a bridge; and/or   the retaining member is between the first arch and the second arch in the immediate vicinity of the contact blade in the closed position.       

   According to other features that are preferred for the same reasons:
         the base and the cap are articulated to each other, the device having an open position in which the cap is raised relative to the base, the cap being pivoted onto the base in the closed position; and/or   the base and the cap are articulated on the side opposite the compartment; and/or   the base and the cap are articulated in a direction transverse to the direction of the compartment; and/or   the base and the cap are articulated by hinge members that are part of the base and pins that are part of the cap.       

   According to other features that are preferred for the same reasons:
         the base and the cap comprise clipping members for fixing them to each other in the closed position; and where applicable   the clipping members are situated on respective opposite sides of the contact blade; and/or   the clipping members comprise clips forming part of the base; and where applicable   the clips form part of a molded plastic material insert of the base; and where applicable   the insert comprises a portion disposed between a metal body of the base and the contact terminal, which is part of the base.       

   According to other features that are preferred for the same reasons and may be used independently of the features set out hereinabove when the connection device comprises a base and a cap:
         the contact terminal is part of the base which comprises a conductive material partition at least partially surrounding a portion of the contact terminal in which the central core is adapted to be engaged; and where applicable   the cap has a portion forming a dome fitting to one of the ends of the partition in the closed position; and where applicable   the cap portion forming a dome comprises a portion of a back wall and a rib; and/or   the partition faces, on the inside, a conductive portion of the base and the cap comprises a wall in which one end of the portion nests in the closed position.       

   According to other features that are preferred for the same reasons:
         the contact terminal comprises a lyre contact adapted to interengage with the central core of the cable and a tail forming part of a receptacle for receiving a coaxial cable connection plug; and where applicable   the receptacle comprises a tubular member in which the tail is engaged and the base comprises an insulative material insert disposed between a body of which the tubular member is part and the contact terminal; and where applicable   the insert comprises a foot accommodated in the tubular member and a head in which the lyre contact is accommodated; and where applicable   the head comprises a first compartment in which the lyre contact is accommodated and a second compartment connected to the first compartment by a passage; and where applicable   the insert comprises a shield connected to the head on the same side as the first compartment and a hole is formed in the shield through which the conductive core of the coaxial cable is passed; and/or   the contact terminal is oriented in a direction transverse to the direction of the compartment.       

   According to other features that are preferred for their effect of centering the base and the cap, which is favorable to achieving good performance from the device of the invention, either the base or the cap comprises a rib accommodated in a groove or notch in the base or the cap, respectively. 
   The explanation of the invention now continues with the description of one embodiment given hereinafter by way of nonlimiting and illustrative example and with reference to the appended drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a device according to the invention, to which a coaxial cable is connected, this device forming a mechanism for a wall-mounted television or FM radio socket. 
       FIG. 2  is an exploded perspective view of the device with the cap raised, showing a coaxial cable in position ready to be placed in the base. 
       FIG. 3  is a perspective view of the cap, showing its interior from a different angle to  FIG. 2 . 
       FIG. 4  is a perspective view of the assembled base. 
       FIG. 5  is a view in elevation of the device shown in  FIG. 1  and the cable to which it is connected in section on a longitudinal plane of symmetry. 
       FIG. 6  is a view similar to  FIG. 5  for a variant of the device in which the connector is an F connector rather than a female IEC connector. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The device  1  shown in  FIGS. 1 to 5  comprises a base  2  and a cap  3 . It is intended to be connected to a coaxial cable  4 , in this example a cable for distributing television and/or FM radio signals. 
   This kind of cable has an insulative plastic material outer jacket  5 , a braid  6  made of fine conductive metal wires, an insulative plastic material inner sheath  7 , and a central core  8  consisting of a relatively rigid conductive metal wire. The inner sheath  7  closely surrounds the core  8 , the braid  6  closely surrounds the inner sheath  7 , and the outer jacket  5  closely surrounds the braid  6 . 
   The cap  3  and the distribution cable  4  are designed to be disposed on the interior side of the socket while on the external side there is a connector  9  for connecting one end of a cord connecting the socket to a television and/or an FM radio receiver. 
   As seen more particularly in  FIG. 2 , the base  2  of the socket  1  comprises a body  10 , an insert  11  and a contact terminal  12 . 
   The body  10  is cast from a conductive metal. It comprises a plate  15  having, on the side that is at the bottom in the drawings, a flat face  16  ( FIG. 5 ) from which projects a tubular member  17  that is part of the connector  9 . 
   The plate  15  has a rectangular contour whose width corresponds to a predetermined dimension common to a series of electrical installation accessories, for example a width of the order of 22.5 mm, and whose length is approximately twice its width. 
   An opening  18  in the plate  15  forms an extension of a bore in the tubular member  17 . 
   In the vicinity of one of the transverse edges of the plate  15  the body  10  has two semicircular hinge members  19  projecting from the face  20  of the plate  15  opposite the face  16 . The hinge members  19  are for articulating the cap  3  to the body  10 , more generally to the base  2 . 
   From the face  20  of the plate  15  there also projects a cage  21  situated between the opening  18  and the transverse edge of the plate  15  opposite that on which the hinge members  19  are located. The width of the cage  21  is approximately half the width of the plate  15 . 
   Over about half of its circumference, on the side opposite the cage  21 , the opening  18  is bordered by a partition  22  whose shape is that of a short length of guttering. The partition  22  projects from the base  20  of the plate  15 . 
   A groove  23  is recessed into the base  20  of the plate  15 . 
   The groove  23  has a generally rectangular shape. One of its shorter sides is oriented in the transverse direction and disposed in the vicinity of the hinge members  19 , which are situated between the groove  23  and one of the transverse edges of the plate  15 . The two longer sides of the groove  23  are oriented in the longitudinal direction and situated in the vicinity of the lateral edges of the plate  15 . The other shorter side of the groove  23  is oriented in the transverse direction and disposed in the vicinity of the transverse edge of the plate  15  adjacent the cage  21 , this shorter side being discontinuous in that it is formed of two sections situated on respective opposite sides of the cage  21 . 
   A rib  24 , also projecting from the face  20  of the plate  15 , is disposed between the groove  23  and the partition  22 . The rib  24  runs along the shorter side of the groove  23  situated in the vicinity of the hinge members  19  and a portion of each of the two longer sides of the groove  23 . 
   Beyond the partition  22 , the rib  24  is extended along each longer side of the groove  23  and about half way along the cage  21  by a straight wall  25  offset from the cage  21 . 
   Each corner of the groove  23  situated on one side of the cage  21  has a right-angle wall  26  running along it. 
   The cage  21  delimits a compartment  27  with a generally cylindrical contour whose diameter corresponds to the outside diameter of the cable  4  and whose axis  51  is situated in the longitudinal plane of symmetry of the body  10  and inclined toward the plate  15  and toward the opening  18 , as seen more particularly in  FIG. 5 . 
   Between the plate  15  and the compartment  27  the cage  21  has a solid cradle  28  delimited on the side of the compartment  27  by a semicylindrical surface. 
   On the side of the transverse edge of the plate  15  opposite the hinge members  19  the cradle  28  is joined to an arch  29  whose inside surface is semicylindrical and extends the inside surface of the cradle  28 . Thus the cage  21  has along the transverse edge of the plate  15  opposite the hinge members  19  a continuous cylindrical contour delimiting an entry mouth into the compartment  27 . 
   The cage  21  comprises an arch  30  similar to the arch  29  opposite the arch  29 , i.e. on the same side as the opening  18 . 
   The arch  30  carries a contact blade  31  whose general shape is that of a fingernail. 
   To be more precise, the blade  31  has an arcuate profile whose radius corresponds to that of the braid  6  of the cable  4 . The blade  31  is disposed concentrically with the compartment  27 . The concave side of the blade  31  faces toward the cradle  28  and its convex side faces toward the arches  29  and  30 . 
   The blade  31  is connected to the arch  30  by a bridge  32  extending between the arch  30  and the end of the blade  31  on the same side as the opening  18  (its proximal end). 
   As may be seen in  FIG. 5 , the blade  31  is slightly longer than the remainder of the cage  21 , its distal end (the end opposite the bridge  32 ) projecting slightly beyond the arch  29 . 
   The distal end of the blade  31  is pointed, i.e. its width, to be more precise its angular extent, becomes progressively smaller toward this end. Its edge surface is additionally thinned, i.e. the blade  31  has a thickness that decreases toward its distal end in the vicinity of the latter. 
   As may be seen more particularly in  FIG. 4 , the blade  31  has a flat  33  extending between the arch  29  and the arch  30  opposite the plate  15 , i.e. on its convex side. 
   At the center of the flat  33  is a groove  34  extending in the longitudinal direction. The groove  34  has a V-shaped profile. 
   The portion of the blade  31  situated between the arches  29  and  30  is accessible from the outside of the cage  21 , both from opposite the cradle  28  and laterally from each side. 
   The insert  11  is molded from an insulative plastic material. 
   It comprises a foot  35 , a head  36 , a shield  37 , two arms  38  and two clips  39 . 
   The foot  35  and the head  36  are oriented in the axial direction and are aligned with each other. 
   As may be seen more particularly in  FIGS. 4 and 5 , the head  36  and the shield  37  delimit a compartment  40  into which a bore in the foot  35  opens. Opposite the shield  37 , the head  36  delimits another compartment  41 . A central passage  42  is formed between the compartment  40  and the compartment  41 . 
   A hole  43  in the shield  37  provides a passage between the compartment  40  and the outside. 
   The passage  42  and the hole  43  are centered on the longitudinal plane of symmetry of the insert  11 . 
   The arms  38  are oriented in the longitudinal direction. Each is rooted at one end at the junction between the foot  35 , the head  36  and the shield  37 . They project from the shield  37  on the side opposite the compartment  41 . 
   The distance between the arms  38  substantially corresponds to the width of the cage  21 . 
   The clips  39  are oriented in the axial direction. Each is rooted laterally on the outside of one of the arms  38 , opposite the shield  37 . Each clip  39  projects from the arm  38  to which it is attached, on the same side as the head  36  and the shield  37 . 
   At the distal end of each of the arms  39  is a detent  44 . 
   The contact terminal  12  is a relatively flexible conformed conductive metal strip. 
   The terminal  12  is oriented in the axial direction. It comprises a tail  45 , a lyre contact  46  and a connecting bridge  47  between the tail  45  and the lyre contact  46 . 
   The tail  45  is globally tubular and has a slot  48  oriented in the axial direction running its whole length. 
   The lyre contact  46  comprises two lips  49  with a globally V-shaped profile. The tops of the lips  49  are oriented in the axial direction and are substantially aligned with the slot  48 . 
   There is a hole  50  in the lyre contact  46  opposite the lips  49  ( FIG. 5 ). 
   The insert  11  is simply nested in the body  10 . 
   In the assembled state, the foot  35  is housed in the tubular member  17  and the opening  18 , the head  36  is surrounded by the partition  22  and by the cage  21 , with the shield  37  disposed against the arch  30 , and the arms  38  are disposed between the cage  21  and the walls  25  and  26  against the face  20 . The root of the clips  39  is disposed between the walls  25  and  26  and the detents  44  are in the space between the arches  29  and  30 . 
   The contact terminal  12  is also nested in the body  2 , to be more precise in the insert  11 . In the assembled state ( FIGS. 4 and 5 ) the lyre contact  46  is disposed in the compartment  40 , the bridge  47  and a portion of the tail  45  are disposed in the bore in the foot  35 , and the remainder of the tail  45  projects from the foot  35  into the tubular member  17 . 
   The lips  49  of the lyre contact  46  face the shield  37  and are centered relative to the hole  43 . 
   The passage  42 , the hole  50 , the lips  49  and the hole  43  are centered in the longitudinal plane of symmetry of the body  2  with the holes  43  and  50  aligned with the compartment  27 , i.e. centered on the same axis  51  ( FIG. 5 ). 
   The cover  3  is cast from a conductive metal. 
   Its overall shape is that of a parallelepipedal box. 
   The edge surface of its lateral wall has substantially the same conformation as the groove  23  of the body  10 . 
   In the vicinity of one of the shorter sides of the edge surface of the lateral wall, the cap  3  has on the outside two aligned pins  55  oriented in the transverse direction. Each pin  55  projects from a rib  56  itself projecting from the lateral wall of the cap  3 , to be more precise from a section of that lateral wall oriented in the transverse direction. 
   The opposite section of the lateral wall, i.e. the other section of this wall that is oriented in the transverse direction, has a central opening  57  whose contour corresponds to that of the cage  21  at the level of the arch  29 . 
   Each of the sections of the lateral wall of the cap  3  oriented in the longitudinal direction has an aperture  58  in the vicinity of the transverse section in which the opening  57  is formed. 
   The apertures  58  are substantially the same width as the clips  39 . They extend from a surface  59  parallel to the edge surface of the lateral wall to the back wall of the cap  3 , in which the apertures  58  are partly formed. 
   A central rib  61  oriented in the longitudinal direction projects from the inside face  60  of the back wall of the cap  3 . The rib  61  is the same width as a notch  62  in the partition  22  of the body  10 . 
   A U-shaped profile rib  63  also projects from the face  60  of the back wall of the cap  3 . The curved portion of the rib  63  has an external contour corresponding substantially to the internal contour of the partition  22 . 
   Another rib  64  that is slightly curved but generally oriented in the transverse direction projects from the face  60  and is joined at each end to one of the ends of the rib  63 . 
   The distance between the end of the rib  61  on the same side as the ribs  63  and  64  corresponds to the distance between the notch  62  and the edge surface of the shield  37 . 
   An arcuate rib  65  oriented in the transverse direction projects from the face  60  and is disposed against the rib  64 , on the side opposite the rib  63 . 
   Two claws  66  projecting from the wall  60  each have a pointed end. The claws  66  are between the opening  57  and the rib  65  and are centered in the longitudinal plane of symmetry of the cap  3 . Two lugs  67  project from the face  60  on respective opposite sides of the claws  66 , at the same level as the apertures  58 . 
   The facing faces of the lugs  67  have a V-shaped profile. They have a relatively sharp edge  68  at each end, at the junction with a lateral face. 
   The cap  3  also has a groove  69  ( FIG. 1 ) recessed with respect to the outside face of its back wall and whose width substantially corresponds to that of the central core  8  of the cable  4 . The length of the groove  69  corresponds to that over which it is necessary to bare the core  8 , as explained later. The groove  69  therefore provides the user with a template enabling him to tell if the bared portion of the core  8  is the required length. 
   The base  2  and the cap  3  are assembled simply by inserting the pins  55  into the hinge members  19 . 
   The cooperation of the pins  55  and the hinge members  19  provides an articulation between the base  2  and the cap  3  about a pivot axis oriented in the transverse direction in the vicinity of the transverse edge of the plate  15  opposite that at the same end as the entry mouth into the compartment  27 . 
   The cap  3  may therefore pivot relative to the base  2  between the raised position shown in  FIG. 2  and the closed position shown in  FIG. 1 . 
   How a coaxial cable  4  is connected to the connection device  1  is described next. 
   The end of the cable  4  is first bared as far as the central core  8  over a predetermined length corresponding to the lengths of the groove  69 , as shown in  FIG. 2 . 
   Then, with the cap  3  raised, the cable  4  is forcibly inserted as far as possible into the compartment  27 , so that the contact blade  31  spears it between its outer jacket  5  and its braid  6 . 
   As this happens, the central core  8  of the cable  4  passes through the hole  43  in the shield  37 , becomes engaged between the lips  49  of the lyre contact  46  of the contact terminal  12  and then a portion  8  of the bared core  8  passes or not through the hole  50 , depending on the bared length and how far the cable  4  is pushed into the compartment  27 , and is accommodated in the passage  42  and in the compartment  41 , as shown in  FIG. 5 . 
   By looking at the lyre contact  46 , the operator can check visually that the core  8  is correctly in place. 
   To complete the connection of the cable  4 , it then suffices to pivot the cap  3  to the position shown in  FIGS. 1 and 5 . 
   At the end of the pivoting movement of the cap  3 , the claws  66  penetrate the outer jacket  5  of the cable  4  and the detents  44  on the clips  39  fit into the apertures  58 . 
   In the closed position ( FIGS. 1 and 5 ), the cap  3  is locked to the base  2  by the clips  39 , the right-angle face of the detent  44  on each of the clips  39  then being against the face  59  of the corresponding aperture  58 . 
   The cable  4  is retained in the device  1  by the claws  66  and by the lugs  67 , each of which is disposed in one of the lateral spaces between the arches  29  and  30 , the sharp edges  68  being pressed against the outer jacket  5  and wedging it against the blade  31 . 
   It will be noted that the clipping means, consisting of the clips  39  and the apertures  58 , are on respective opposite sides of the retaining members consisting of the claws  66  and the lugs  67 , more generally on respective opposite sides of the contact blade  31 . 
   The locking action between the base  2  and the cap  3  is therefore effected as close as possible to these retaining members, which is beneficial to the resulting quality of retention. 
   The arch  29  of the cage  21  is disposed in the opening  57  with the same contour as the cap  3 , the external face of the cage  21  and that of the cap  3  being flush with each other, as may be seen in  FIG. 1 . 
   The arch  30  of the cage  21  is nested in the hollow of the rib  65 . The rib  64  is placed against the edge surface of the shield  37  and the rib  63  is nested against the top of the partition  22 , on its inside. 
   The edge surface of the lateral wall of the cap  3  is disposed against the face  20 , around the groove  23 , which receives a tongue  52  running along the inside edge of the edge surface of the lateral wall of the cap  3  and projecting relative to that edge surface. 
   It will be noted that the back wall of the cap  3  forms with the ribs  63  and  64  a kind of dome which, with the partition  22 , forms a shell enveloping the bared portion of the central core  8  and the lyre contact  46  of the contact terminal  12  to ensure good continuity between the shielding braid  6  of the cable  4  and the shielding provided by the device  1 . This continuity is beneficial to the performance of the device  1 , in particular with regard to electromagnetic compatibility (EMC). 
   Finally, the groove  61  is accommodated in the notch  62 , their cooperation during the closing of the cap  3  centering the latter relative to the body  2 . 
   In the embodiment shown in  FIGS. 1 to 5 , the connector  9  is of the female IEC type, the tubular member  17  being adapted to receive the tubular member of a corresponding plug inside it and the tail  45  being adapted to receive the pin of the plug inside it. 
   The variant  1 ′ of the device  1  shown in  FIG. 6  is identical except that the connector  9  is replaced by an F-type connector  9 ′. 
   To be more precise, the body  10  is replaced by a body  10 ′ in which the tubular member  17  is replaced by a tubular member  17 ′ having an external screwthread, the insert  11  is replaced by an insert  11 ′ in which the foot  35  is replaced by a foot  35 ′ extending the whole length of the tubular member  17 ′, and the terminal  12  is replaced by a terminal  12 ′ in which the tail  45  is replaced by a tail  45 ′ adapted to receive inside it a bared end portion of the central core of a coaxial cable. 
   In a variant that is not shown, the connector  9  is replaced by a male IEC connector or by a connector of some other type. 
   In other variants which are not shown, the number of claws like the claws  66  is different, i.e. there is only one claw or more than two claws; likewise the lugs  67 ; there is only type of retaining member like the claws  66  and the lugs  67  or more than two types; and/or the retaining members opposite the contact blades such as  31  on the insulative outer jacket  5  and providing a grip are shaped differently. 
   In further variants of the device  1  that are not shown, it is not integrated into a wall-mounted socket but into some other form of connection device, for example a plug to be fitted to one end of a coaxial cable. In this latter case, and moreover in other variants, the connector such as  9  or  9 ′ is aligned with the compartment such as  27 , not at right angles to it; the cap such as  3  is articulated about a pivot axis situated elsewhere than at the opposite end to the entry mouth into the compartment such as  27 , for example at the same end as the entry mouth; the cap such as  3  is replaced by a cap that is not articulated to the base such as  2 , for example a separate cap merely clipped to the base such as  2 ; and/or the body such as  10  and the cap such as  3  are made from a conductive material other than a metal, for example from a plastic material covered with a conductive film. 
   Numerous other variants are possible as a function of circumstances, and in this connection it is pointed out that the invention is not limited to the examples described and shown.