Abstract:
A shielded electrical connector in which the shield cover is formed as two U-shaped parts, each of which includes an integral clamping portion for clamping with a shielded connector. The clamping portions are connected to the cover parts by leg portions. An insulator containing electrical contacts is sandwiched between the cover parts after the cable is attached to the contacts. The cover parts are compressed together, following which the clamp portions are clamped about the cable to provide electrical connection between the cable and the shield cover.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to shielded electrical connectors. 
     2. Description of the Prior Art 
     In the mutual connection between high frequency machines, it becomes necessary to eliminate the effect of an external noise in the connecting cable, etc. Generally, therefore, a shielded cable is employed as a connecting cable and, at the same time, the plug connector which is used for connection is provided with an electroconductive cover, where the external jacket of the shield for the cable is connected. 
     At the time when this connector has been inserted into the receptacle of a high frequency machine, along with the mutual connection among the contacts, the cover of the plug connector is electrically connected with an electroconductive cover of the receptacle, with a result that the outer cover of the shield may be grounded through the housing of the high frequency machine in the receptacle. 
     In the case of the conventional connector, however, the number of parts involved is relatively large, with a consequence that it is troublesome and relatively expensive to manufacture. In addition, the connecting operation becomes complicated and, moreover, the shielding effect is insufficient. 
     A prior art connector is shown in FIG. 1, and includes a connector A having an insulator 2 supporting contacts 1 having connection terminal elements 1a. Connector A is provided with electrically conductive covers 3 and 4 which may have flanges 3a and 4a that are integrally joined respectively in the screw insertion holes 3b, 4b (only holes 4b are visible). A flat and generally tubular shield cover B is used which has a cable withdrawal hole 5a at one end and with screw receptacles 5b at the other end. Shield cover B has an opening 5d surrounded by a flange 5c. A cable clamp C comprising first and second metal members 7 and 8 and a tightening screw 6 is fixed to cover B adjacent cable withdrawal hole 5a thereof by such means as soldering. 
     Accordingly, the total number of component parts of the prior design reaches as many as nine, with a result that the structure involved becomes complicated and that the price also rises accordingly. 
     In regard to the connection of the cables, moreover, one end of the cable 9 is inserted into the shield cover B through the metal clamp C and the cable withdrawal hole 5a and is pulled out of the opening 5d, followed by the connection of the base wires with the connection terminal elements 1a of the connector A. 
     Thereafter, the connector A is fixed to the opening part 5d of the shield cover B by means of a female screw hole 5b and installation screws 10 extending into receptacles 5b and the cable 9 which has been passed into the metal clamp C is finally tightened by tightening screws 6. After assembly, the shield outer cover 9a of the cable will have to be electrically connected with the shield cover B and, at the same time, it will have to be mechanically fixed. 
     Accordingly, the prior art construction is not only complicated but the connecting operation is also troublesome. Since the shield cover B is tubular, moreover, should it be forgotten to install shield cover B over the cable 9, it becomes necessary to release the connection between the connector and the cable which have already been connected, install the shield cover and again connect the connector. 
     Moreover, the metal clamp C is made so as to be able to clamp against cables having diameters which are within a certain range. The cable withdrawal hole 5a is also chosen in accordance with the same principle. As a result, if the diameter of the cable is small as compared with the size of the hole, tightening becomes dissatisfactory and, accordingly, there develops a possibility of grounding becoming dissatisfactory. Moreover, a leakage of electric waves takes place from the gap between the cable withdrawal hole 5a of the shield cover B and the cable 9. Because of this, there is a shortcoming in that the shielding effect becomes dissatisfactory. 
     It would be desirable to provide a connector which is small in size and low cost, which has a shielding effect and which eliminates various kinds of shortcomings experienced in a conventional connector as has been described above. 
     SUMMARY OF THE INVENTION 
     In accordance with this invention, there is provided in a shielded electrical connector including at least one electrical contact supported by a supporting insulator, a shield cover for the connector and a cable clamp for engaging a cable adapted to be connected with the connector, the improvement comprising: 
     the shield cover being formed of separate top and bottom overlapping parts adapted to be compressed to each other so as to sandwich the insulator therebetween, and 
     cable clamp means integrally formed with each of the top and bottom parts and adapted to engage with the cable after the top and bottom parts are overlapped on the insulator, so that the cable is electrically connected to the shield cover. 
     Preferably, the cable clamp means are in the form of compressible U-shaped portions connected by leg portions to the top and bottom parts of the shield cover. Also, the rear portion of each of the top and bottom parts are provided with openings which form a cable receiving entryway. Positioning means and retention means are preferably also provided. 
     The connector of this invention has a reduced number of parts, can be small in size, can be easily manufactured and is readily connected to a shielded cable. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1a is a perspective view of a prior art connector before assembly. 
     FIG. 1b is a perspective view of the connector of FIG. 1a after assembly. 
     FIG. 2 is an exploded perspective view of the connector of this invention before connection to a cable. 
     FIGS. 3a, 3b and 3c show the assembly of the connector of FIG. 2 to a cable. 
     FIG. 4 is an enlarged partial cross-section view of the connector retained within the shield cover by retention means. 
     FIG. 5 is a perspective view of the connector having a molded cover. 
     FIG. 6a is a perspective view of the connector which includes means to maintain the opening at the front of the connector in an open position. 
     FIG. 6b is an enlarged partial cross-section view of the front of the insulator shown in FIG. 6a. 
     FIG. 7 is an enlarged partial cross-section view of a male connector. 
     FIG. 8 is an enlarged partial cross-section view showing the retention of the insulator in the cover shield. 
     FIG. 9a is a perspective view of an alternate embodiment of the cable clamp of the connector. 
     FIG. 9b is a cross-section view of the cable clamp of FIG. 9a. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to FIG. 2, in accordance with this invention connector A (shown as a female connector) comprises contacts 1 supported in an insulator 2. The shield cover is in the form of first and second shield cover forming parts 11 and 12. The forward end of shield cover forming parts 11, 12 forms an opening for the insertion of another connector, and the rear end of parts 11, 12 has an opening 14 for withdrawal of cable 9, as shown in FIG. 3b. Parts 11, 12 are shaped so as to overlap each other to form a U-shaped cross-section dimensioned to envelop connector A without any gap. At the rear of each part 11, 12, a generally U-shaped clamping portion 11a, 12a is formed, which portions are integrally connected with parts 11, 12 by connecting legs. The connecting leg connecting clamping portion 12a to part 12 is longer than the leg connecting clamping portion 11a to part 11, such that when assembled with a cable 9 (FIG. 3b), each clamping portion 11a, 12a separately clamps against cable 9 and are spaced from each other. Clamping portions 11a and 12a are formed of compressive metal for ease in clamping cable 9. 
     As shown in FIG. 3a, for the connection of cable 9 to insulator 2, first the cable cover is stripped back to expose shield external jacket 9a, which is folded back on the cable. The individual conductors are then joined by soldering or other means to contacts 1. Preferably, an aluminum tape 15 is wound about the end of cable 9, which tape is electroconductive with cable 9, in order to increase the diameter of the cable at its terminating end with respect to cable withdrawal hole 14. This prevents any gap between cable 9 and cable withdrawal hole 14, so that it is possible to obtain a satisfactory shielding effect. In the next step, shield cover forming parts 11, 12 are sandwiched about insulator 2, and compressed together. Clamping portions 11a, 12a are compressed against cable shield jacket 9a, with a suitable compressive metal tool, such that the cable is connected to the shield cover. Shield cover forming parts are also compressively joined with each other. 
     Since the number of constituent parts required in this connector is less than one half of the conventional connector, the manufacturing steps become simple accordingly and the size of the product can be reduced accordingly. Moreover, costs are reduced and the connecting operation is simplified. Since there is no need to pass the cable through the shield cover as in the conventional method and there is no danger of connecting the cable with the connector at all, there will be no requirement of going through the trouble of reconnection as a result of the same. 
     According to this invention, therefore, it becomes possible to supply small-sized and low-priced connectors whose production is easy and whose connecting operation is simple, which has eliminated the shortcomings of the conventional connectors and which is equipped with the shield function. 
     When the number of electrodes in a connector becomes large, the contact pressure between the contacts themselves of the opposite connectors which have been fixed to the panel becomes large. Because of this, in the case where the maintenance of the connector A due to the shield covers 11 and 12 becomes insufficient, the connector A is pushed in a direction which is opposite to the direction of insertion due to the force of opposition based on the contact pressure between the contacts themselves at the time when it is inserted into the opposite receptacle connector which has been fixed to the panel, etc., with a result that shield covers 11 and 12 move forward ahead of the connector A and there is a danger that the connecting terminal element of the contact that has been exposed may contact the inner surface of the shield cover. 
     To avoid such problem, in one embodiment of this invention there is provided a position regulating protrusion 2c on the upper and lower surfaces of the holding insulator 2 of the connector A as shown in FIG. 2 (only the upper protrusion being visible), and drop-in holes 11b and 12b are provided for the positional regulating protrusions 2c at the corresponding parts of the shield cover forming parts 11 and 12 respectively. The assembled position is shown in FIG. 4, with protrusions 2c being retained within holes 11b, 12b. As a result, the position of connector A within the shield cover is fixed from longitudinal movement. 
     It is also possible to mold a plastic housing around the assembly from a synthetic resin 16, as shown in FIG. 5, thereby increasing the holding force of the connector A. In the case where the number of electrodes has increased and the size of the connectors becomes large, furthermore, there is a corresponding increase in the thickness of the sheet of the shield covers 11 and 12 and, accordingly, the thickness of the compressive metal clamps 11a and 12a which have been formed by extrusion integrally with the same also increases. 
     Accordingly, a large force will be required for compressive adhesion, with a result that it becomes increasingly difficult to continue manual clamping in such a manner that the opening for the insertion of the opposite receptacle connector may not be fully open. To avoid this, a shown in FIGS. 6a and b, a support protrusion 2d is formed on part 2 and, at the same time, a support recess 2e is provided in the direction of the thickness of the support protrusion on the side surface. 
     Moreover, as shown in FIGS. 6a and b, support protuberant pieces 11c and 12c which can enter the aforementioned support recess 2e are provided at both side terminals of the shield cover forming parts 11, 12 on the side of the opening for the insertion of the opposite connectors, so that the shield cover forming parts 11 and 12 may not open at the time of the compressive adhesion of the compressive metal clamps 11a and 12a. 
     Since, in such a case, the support protrusion 2d which has been provided on the holding insulator 2 of the connector at the time of the insertion into the opposite connector abuts against the tip of the shield cover forming parts 11 and 12, there is an effect of preventing the shield covers 11 and 12 moving forward of the connector A at the time of the insertion into the opposite connector. 
     It is mentioned in this connection that the support protrusion 2d on the side of the holding insulator 2 may be provided for such a length as is necessary for forming the support recess part 2e. Moreover, even though an explanation has been given above by using the female connector as an example, it is only necessary in the case of a male connector to effect covering by the shield cover forming parts 11 and 12 in such a manner as to cover the side surface of the protuberant male contact 1 as shown in FIG. 7. 
     In connection with the retention of the holding insulator 2 to the shield cover forming parts 11 and 12, moreover, it is only necessary to provide a support recess 2f above and below the terminal face of the holding insulator 2 as shown in FIG. 8, for instance, and provide L-shaped support arms 11d and 12d that enter the support recesses 2f on the side of the shield cover forming parts 11 and 12. 
     In the above embodiment, compressively adhered metal clamps 11a and 12a are provided at different positions at one terminal of the shield cover forming parts 11 and 12, thereby compressing the cable 9. However, it is also possible to compressively adhere the compressive metal clamps 11a and 12a at the same locations as shown in FIGS. 9a and 9b. 
     As is clear from the above explanation, this invention provides a small-sized and low-cost connector equipped with a sufficient shielding function, whose production is easy to achieve and in which the connections are easy to carry out.