Patent Publication Number: US-2003232533-A1

Title: Plug connector comprising a movable plug piece receptacle

Description:
TECHNICAL FIELD  
       [0001] The invention relates to a plug socket into which a complementary plug piece can be inserted in order to establish a plug connection.  
       BACKGROUND OF THE INVENTION  
       [0002] With all plug connections there basically is the problem that on the one hand during inserting the plug piece in the plug socket it has to be ensured that the plug piece is properly aligned in relation to the plug socket, or tht measures are taken which allow to have tolerances balanced. Otherwise it can not be guaranteed that the conductors to be connected are contacted properly. The problem of misalignment is the more severe the more contacts have to be plugged together and the narrower the spacing is between these contacts. Especially in case the plug piece is a circuit board provided with a multiplicity of conductor tracks arranged close to each other, it is of particular importance that these conductor tracks are contacted with positional accuracy.  
       [0003] It is the object of the invention to provide a plug socket by means of which the conductors of a plug piece, in particular of a circuit board, can be contacted with high accuracy.  
       BRIEF SUMMARY OF THE INVENTION  
       [0004] According to the invention, a plug socket comprises a housing. Arranged in the housing is a plug piece receptacle made of an insulating material, the receptacle being movable between an initial position and a plug-in position. The plug socket further includes a plurality of contact elements which serve for making contact with a plug piece inserted in the receptacle and are accommodated in the plug piece receptacle, and at least one spring which urges the plug piece receptacle into the initial position. As the plug piece receptacle is movable, it will be properly aligned during inserting the plug piece despite any positional tolerances, so that the contact elements arranged on the plug piece receptacle are able to make contact with the conductors of the plug piece associated thereto with positional accuracy.  
       [0005] According to a preferred embodiment provision is made that the plug piece receptacle has a rectangular cross section and the contact elements are arranged on one of the broader side walls of the plug piece receptacle. Such plug piece receptacle is particularly suitable for receiving a circuit board as the plug piece, which board can be pushed into the interior space of the plug piece receptacle with a very small clearance. In is arrangement, the contact elements are arranged such that they make contact with conductor tracks provided on the upper and lower sides of the circuit board.  
       [0006] It is preferably provided that the contact elements are movably arranged in the side wall of the plug piece receptacle, Tis measure likewise serves for balancing tolerances, namely in terms of the thickness of the plug piece; the contact elements will be forced outwards during inserting the plug piece and glide on the surface thereof until they make contact with the appropriate conductors. Contact balls, for instance, are particularly suitable for being used as contact elements, these balls being received in a bore in the side wall of the plug piece receptacle. Basically, all other contact elements are suited as well, for instance cylindrical contact elements or pins.  
       [0007] Here it is preferably provided that the contact elements are elastically urged towards the interior space of the plug piece receptacle. In this way the required contact force is ensured whilst at the same time it is possible to balance any tolerances that might exist.  
       [0008] According to the preferred embodiment of the invention it is provided that the spring urging the plug piece receptacle into the initial position also urges the contact elements towards the interior space of the plug piece receptacle. The result is a particularly simple construction with few components, because the spring has a dual function.  
       [0009] It is preferably provided that the spring is a U-type spring having an abutment end and a supporting end, the abutment end resting at the housing and the supporting end being supported by the contact elements, so that the latter are urged towards the interior space of the plug piece receptacle. It is in this way that the forces exerted on the spring by the contact elements are directly taken up by the housing.  
       [0010] According to the preferred embodiment of the invention it is provided that the spring is fastened to the plug piece receptacle, so that it is entrained by the plug piece receptacle when the latter is moved from the initial position into the plug-in position. This makes it possible during moving the plug piece receptacle to vary the force exerted on the contact elements by the spring. This may be effected, for example, in that the housing has an abutment face for the abutment end of the spring and that the abutment face extends obliquely in relation to the moving direction of the plug piece receptacle, so that the spring is increasingly bent when it is moved, together with the plug piece receptacle, from the initial position into the plug-in position. It is in this way that only small abutment forces will act during pushing the plug piece into the plug piece receptacle, so that the contact elements glide on the surface of the plug piece with low friction. It is not until the plug piece has been fully pushed into the plug piece receptacle and there is no relative motion any more between the plug piece and the plug piece receptacle that the contact force rises to the actually required value.  
       [0011] It is preferably provided that the abutment face, at its front end as seen in the moving direction of the plug piece receptacle, is provided with a recess which is engaged by the abutment end of the spring if the plug piece receptacle is in the initial position. The recess together with the abutment end of the spring makes sure that the initially required force to move the plug piece receptacle out of its initial position is larger than the force which is required for pushing the plug piece into the plug piece receptacle.  
       [0012] According to the preferred embodiment of the invention it is provided that a flexible conductor foil is arranged between the supporting end of the spring and the contact elements, the conductor foil being fastened to the plug piece receptacle and to the housing as well. A flexible conductor foil is particularly suited to establish the connection to the movably arranged plug piece receptacle, because the conductor foil can follow the shifting motion of the plug piece receptacle without any problems.  
       [0013] It is preferably provided that the interior space of the plug piece receptacle has an area, situated between the entrance port for the plug piece and the contact elements, which expands towards the entrance port in the nature of a pilot funnel. This measure facilitates the insertion of the plug piece in the plug piece receptacle.  
       [0014] According to the preferred embodiment of the invention two springs are provided so as to be arranged on opposite sides of the plug piece receptacle, and the plug piece receptacle is mounted between the springs in a floating manner. Any tolerances can be balance particularly well in this way. Moreover, it is not necessary to provide expensive guides for the plug piece receptacle. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0015]FIG. 1 shows in a sectional view a plug socket, the plug piece receptacle being in the initial position;  
     [0016]FIG. 2 shows in a schematic, perspective view the plug piece receptacle of FIG. 1 and a plug piece;  
     [0017]FIG. 3 shows in a sectional view the plug socket of FIG. 1, with a plug piece inserted in the plug piece receptacle which still is in the initial position;  
     [0018]FIG. 4 shows in a sectional view the plug socket of FIG. 3, with the plug piece receptacle being in an intermediate position between its initial position and a plug-in position; and  
     [0019]FIG. 5 shows in a sectional view the plug socket of FIG. 4, with the plug piece fully inserted in the plug socket and the plug piece receptacle being in the plug-in position. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     [0020] The construction of the plug socket will now be explained with the aid of FIGS. 1 and 2. The plug socket has a housing  10  which can be fastened to a suitable base by means of a mounting surface  12 . Formed in the housing  10  is an aperture  14  through which a plug piece  5  can be pushed into the housing  10 . The dimensions of the aperture  14  are larger than the dimensions of the plug piece  5 . A pilot ramp  15  is additionally provided on the exterior.  
     [0021] In particular, the plug piece  5  can be a circuit board which is provided with several conductor tracks  7  (see in particular FIG. 2). In the plug piece  5  shown, the conductor tracks  7  are arranged inside and terminate at the surface in contact areas  9 . Departing from the embodiment shown, the conductor tracks  7  could also extend on the surface of the circuit board.  
     [0022] A plug piece receptacle  16  is arranged in the interior of the housing. This receptacle is realized in the nature of a pocket with a rectangular cross section, i.e. has two broader side walls  18 , two narrower side walls  20 , a bottom  22  and an entrance port  24  opposite the bottom.  
     [0023] A plurality of contact elements  26  is arranged or accommodated in the broader side walls  18 ; in this case, the contact elements are realized as contact balls and made of an electrically conductive material. They preferably are coated with gold. The contact elements  26  are each arranged in a bore  27  which is narrowed towards the interior space of the plug piece receptacle  16  such that the corresponding contact element  26  can not come out of the bore  27  on this side.  
     [0024] The cross section and the dimensions of the interior space of the plug piece receptacle  16  correspond, in the area lying between the contact elements  26  and the bottom  22  of the plug piece receptacle, to the dimensions of the plug piece  5 , so that the plug piece  5  is received in the plug piece receptacle  16  with small clearance. In the area of the interior space of the plug piece receptacle  16  lying between the contact elements  26  and the entrance port  24 , the cross section of the interior space slightly expands towards the entrance port  24  such that there is produced a pilot funnel for the plug piece  5 .  
     [0025] Two flexible conductor foils  28 ,  30  are arranged on the exterior of the broader side walls  18  of the plug piece receptacle  16 , which each have several conductor tracks  31 . Each conductor track is associated to one contact element  26 . The conductor foil  28  is arranged on the lower side wall  18  with respect to FIG. 1 and extends in a loop first to the left wall of the housing  10  and from there in downward direction, where it comes out of the housing  10  in the region of the mounting surface  12 . The conductor foil  30  is arranged on the upper side wall  18  of the plug piece receptacle  16  and from there extends to the right and obliquely downwards, likewise coming out of the housing  10  in the area of the mounting surface  12 . Each conductor foil  28 ,  30  is fastened to the plug piece receptacle  16  by several fastening pins  32  formed on the exterior of the side walls  18  and engaging in corresponding openings of the conductor foils  28 ,  30 .  
     [0026] Arranged between the side walls  18  of the plug piece receptacle  16  and the housing  10  is one spring  34  each. Each spring  34  is a U-type spring having an abutment end  36 , a supporting end  38  and a bending section  40  therebetween. The supporting end  38  of each spring  34  rests on the conductor foil  28  and  30 , respectively, in the area under which the contact elements  26  are arranged. Thus, the spring ensures that the conductor tracks of the conductor foil are pressed against the contact elements  26 , so that an electrical contact is established.  
     [0027] The spring  34  is fastened to the plug piece receptacle  16  in its area lying between the supporting end  38  and the bending section  40 . To this end, a laterally arranged web  42  in the plug piece receptacle (see in particular FIG. 2) is provided with a holding projection  44  engaging in a complementary lateral recess of the spring  34 .  
     [0028] In the initial position shown in FIG. 1, the abutment end  36  of the spring  34  is situated in a recess  46  in each case; these recesses are formed in the housing  10  so as to be opposite each other. Each of the recesses  46  is followed by an abutment face  48  which starting from the recess  46  extends to the right regarding FIG. 1, i.e. away from the aperture  14  of the housing  10 . The abutment faces  48  are inclined such that the spacing between them becomes smaller with increasing distance from aperture  14 .  
     [0029] In the initial position shown in FIG. 1 the plug piece receptacle  16  is held in this initial position substantially only by the springs  34 . In the initial position the entrance port  24  of the plug piece receptacle  16  immediately adjoins the aperture  14  in the housing  10 . The plug piece  5  to be inserted in the plug socket is guided into the interior space of the plug piece receptacle  16  by the pilot ramps  15  of aperture  14  as well as by the pilot funnel formed in the plug piece receptacle  16 .  
     [0030] In the course of inserting the plug piece  5  in the plug piece receptacle  16 , the abutment ends  36  engaging in the recesses  46  in the housing  10  ensure that the plug piece receptacle  16  is held in its initial position until the plug piece  5  is fully inserted in the plug piece receptacle  16  and rests at the bottom  22 . The force tat would be required to move the springs  34  to the right regarding FIGS. 1 and 3 and, in so doing, to pull the abutment faces  36  out of the recesses  46 , is in fact larger than the frictional force which during inserting the plug piece  5  is effective between the plug piece receptacle  16  and the plug piece, in particular between the plug piece  5  and the contact elements  26 . As the plug piece receptacle  16  is mounted between the two springs  34  in a floating manner, it automatically assumes the optimal position during inserting the plug piece  5 , so that even in case where the plug piece is inserted skewed in the housing the plug piece  5  will come to lie in the plug piece receptacle  16  in proper position and the contact areas  9  will be underneath the contact elements  26  in their accurate position.  
     [0031] As soon as the plug piece  5  rests on the base  22  of the plug piece receptacle  16  and is further pushed into the plug piece, the plug piece receptacle  16  is entrained in the plug-in direction (see arrow P in FIG. 4), whereby the springs  34  will be entrained by the holding projections  44 , too. In the process, the abutment ends  36  of the spring  34  are pulled out of the recesses  46  and moved towards inside, whereby the springs  34  are bent. The higher spring tension results in the supporting ends  38  applying a higher force on the conductor foil  28  or  30 , this leading to a higher contact force, on the one hand, between the conductor tracks  31  of the conductor foils  28 ,  30  and the contact elements  26  and, on the other, between the contact elements  26  and the contact areas  9  of the plug piece  5 . It is particularly of advantage if this enhanced contact force will act not until there is no relative motion between the contact elements  26  in the plug piece receptacle and the contact areas  9  of the plug piece  5  any more. On the one hand, this facilitates insertion of the plug piece, and on the other band a high friction between the contact elements  26  and the contact areas  9  and a resulting high wear of the contact areas will be prevented.  
     [0032] When the plug piece  5  is pushed further into the plug socket, the plug piece receptacle  16  likewise will be pushed into the housing  10 , until the plug-in position shown in FIG. 5 is reached. In so doing, the pretension of the spring  34  is further enhanced, because due to the inclined profile of the abutment faces  48  they are pre-tensioned more and more until the maximum contact force will be reached finally, as soon as the plug-in position is reached.  
     [0033] As can be taken from comparing FIGS.  3  to  5 , the conductor foils  28 ,  30  follow the shifting motion of the plug piece receptacle  16  without any problem.  
     [0034] If the plug piece  5  is to be pulled out from the plug socket again, all the steps described for the insertion process will occur in the reverse order. First, the plug piece receptacle  16  together with the plug piece  5  will be brought from the plug-in position shown in FIG. 5 into the initial position shown in FIG. 3, before the plug piece  5  is pulled out of the plug piece receptacle  16 . As long as the plug piece receptacle  16  is not in its initial position, the force required for pulling the plug piece  5  out of the plug piece receptacle  16  will be larger than the force required for shifting the plug piece receptacle  16  in the direction towards the initial position. This is due to the fact that the abutment faces  48  are inclined, so that the force acting between the abutment ends  36  and the abutment faces  48  will have a component which biases the springs  34  towards the recesses  46 . At the same time there acts a high frictional force between the contact elements  26  and the plug piece  5 , because the springs  34  are still under mechanical tension.