Patent Publication Number: US-5833495-A

Title: Plug type cable connector

Description:
FIELD OF THE INVENTION 
     This invention generally relates to the art of electrical connectors and a method of making the same. 
     BACKGROUND OF THE INVENTION 
     Generally, an electrical connector typically includes a plurality of terminals which are connected to the conductors of an electrical cable. The terminals usually are mounted in a dielectric body. The connector may include a conductive shield casing for shielding the terminations of the terminals and the conductors from electrical interference. The overall connector may be encased within an outer sheath of insulating material. Still further, a dielectric boot often is positioned about the rear of the connector and a portion of the projecting cable. The boot may be applied by an overmolding process and, in part, functions as a strain relief means for the cable. 
     The fabrication of an electrical connector as described above often is a detailed and inherently inefficient process. The cable initially must be prepared by removing a distal section of its outer cladding and usually stripping insulation from around the conductors to expose the conductors for termination to the terminals which, themselves, must be mounted in the dielectric body. The body must be covered by the shield casing, and the outer sheath must be assembled about the casing before the rear boot is overmolded about the preassembled subassembly. The outer sheath may be formed in two halves and preassembled by a resin material. The outer sheath must be held onto the shield casing during the overmolding process, and means must be provided to prevent the overmolding material from entering the interior connecting cavity. Still further, each two conductors of the cable typically are twisted to prevent leakage of signals to adjacent conductors, and the untwisted length must be shortened as much as possible. All of these processing parameters are difficult to achieve in an efficient manner, and incomplete or defective connectors correspondingly are produced. The present invention is directed to solving this myriad of problems by an efficient connector and method of making the same. 
     SUMMARY OF THE INVENTION 
     An object, therefore, of the invention is to provide a new and improved electrical connector of the character described, along with an improved method of making the connector. 
     In the exemplary embodiment of the invention, the electrical connector includes a dielectric body mounting a plurality of terminals adapted for terminating the conductors of an electrical cable extending rearwardly from the body. A conductive shield casing substantially surrounds portions of the dielectric body and at least the terminations between the terminals and the conductors. The dielectric outer sheath substantially surrounds at least a rear end of the conductive shield casing. A cap is fitted about the cable and covers substantially entirely the rear periphery of the dielectric outer sheath. A dielectric boot is overmolded about the cable, the cap and the rear periphery of the outer sheath. Therefore, the cap prevents ingress of any overmolding material into the sheath and the interior of the connector. 
     As disclosed herein, the dielectric outer sheath is generally cylindrical and extends rearwardly beyond the conductive shield casing and over a front end portion of the cable. A front end of the dielectric body, surrounded by a front end of the conductive shield casing, projects outwardly beyond a front end of the dielectric outer sheath. The cap is fabricated of dielectric material and includes a circumferential groove for receiving a peripheral edge of the dielectric outer sheath. 
     Another feature of the invention includes the provision of latch means operatively associated between the conductive shield casing and the dielectric outer sheath to hold the sheath on the casing during the overmolding process. As disclosed herein, the latch means includes a resilient snap-latch on the dielectric outer sheath engageable with a latch shoulder on the conductive shield casing. Finally, the conductive shield casing includes a portion extending rearwardly for clamping onto a cable shield at a front end of the cable. 
     The invention also is directed to a method of fabricating the electrical connector as outlined above. 
     Other objects, features and advantages of the invention will be apparent from the following detailed description taken in connection with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The features of this invention which are believed to be novel are set forth with particularity in the appended claims. The invention, together with its objects and the advantages thereof, may be best understood by reference to the following description taken in conjunction with the accompanying drawings, in which like reference numerals identify like elements in the figures and in which: 
     FIG. 1 is a longitudinal section through the electrical connector embodying the concepts of the invention; 
     FIG. 2 is a top plan view of the connector; 
     FIG. 3 is a longitudinal section taken generally along line 3--3 of FIG. 1; 
     FIG. 4 is a bottom plan view of the connector; 
     FIG. 5 is a view of the first step in fabricating the connector, including positioning the cap over the electrical cable; 
     FIG. 6 is a view similar to that of FIG. 5, but showing the cable prepared for termination; 
     FIG. 7 is a view of the next step of terminating the cable conductors to terminals in the body; 
     FIG. 8 shows the conductive shield casing mounted to the subassembly of FIG. 7; 
     FIG. 9 is a view similar to that of FIG. 8, at a right-angle thereto; 
     FIG. 10 is a view similar to that of FIG. 8, with the lower part of the shield casing assembled; 
     FIG. 11 is a bottom plan view of the subassembly of FIG. 10; 
     FIG. 12 is a top plan view of the subassembly of FIGS. 10 and 11, but with the dielectric outer sheath mounted thereto; and 
     FIG. 13 is a bottom plan view of the assembly of FIG. 12. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the drawings in greater detail, and first to FIGS. 1-4, the invention is illustrated as embodied in a plug-type electrical connector, generally designated 1, which includes a plug body 2 that can be mated, for example, with a receptacle connector of an appropriate appliance, such as a video camera body or the like. A plurality of terminals 3 are mounted in plug body 2 and have tails 3a soldered to the stripped ends 6 of conductors 5 at the forward end 4a of an electrical cable, generally designated 4. Plug body 2 forms an insulating housing 7 having a front head portion 7a and an enlarged tail portion 7b. Therefore, the lateral distance between the conductors is increased by enlarging the tail portion. The conductors are separated by partitions 7c in tail portion 7b of the plug body. This facilitates soldering the conductor ends 6 to terminal tails 3a and eliminates the necessity of covering the terminal-to-conductor connections. 
     A shield casing, generally designated 8, of conductive sheet metal material substantially surrounds plug body 2 and cable conductors 5. Specifically, the shield casing includes a front head shielding section 8a covering head portion 7a of the plug body, an intermediate shielding section 8b covering the enlarged tail portion 7b of the plug body and conductors 5 of cable 4, and a rear or tail shielding section 8c covering the end of cable 4. The box-like intermediate shielding section 8b includes upper and lower halves. The cylindrical tail shielding section 8c provides a crimping section for clamping around the cable end. The inner shield of the cable is folded back to cover the end of the cable, and an electrically conductive tape 9 is wound about the folded-back shield. Shield casing 8 is connected to plug body 2 and the cable end by crimping tail shielding section 8c about the taped end of the cable. As seen in FIG. 3, head shielding section 8a, intermediate shielding section 8b and tail shielding section 8c are integrally connected by joint portions 10a and 10b. 
     A cylindrical cap 11 is fitted onto cable end 4a and includes a hollow cylinder portion 11a and an annular collar 11b integral with the hollow cylinder. Preferably, the cap is fabricated of dielectric material such as plastic or the like. A prefabricated cylindrical outer sheath 12 of dielectric material is mounted on plug body 12 about conductive shield 8. A tail end of sheath 12 is engaged with the annular collar 11b of cap 11 by positioning a rear peripheral edge 12c of the sheath in a circumferential groove 11c of the cap. Therefore, prefabricated sheath 12 covers a longitudinal portion of the connector from a mid-area of plug body 2 close to the end of tail shielding section 8c of shield casing 8. A forward section 12b of sheet 12 has resilient snap-latches 14 on the inside thereof for latching behind latch shoulders 16 of the head shielding section 8a of shield casing 8. Therefore, the dielectric outer sheath can be mounted on the shield casing and latched thereto during a subsequent overmolding process, while allowing cap 11 to be correctly positioned at the rear of the outer sheath. 
     A dielectric boot, generally designated 18, is overmolded about cable end 4a and includes a forward cylindrical portion 17 overmolded about cap 11 and peripheral edge 12c of outer sheath 12. It can be seen that the outer surface of the cylindrical portion 17 of the boot is generally flush with the rear end 12a of outer sheath 12 so that the boot substantially forms a continuation of the outer sheath. The boot provides strain relief for the cable. Cap 11 prevents ingress of any overmolding material into the inside of the outer sheath, i.e. to the interior of the electrical connector around the shield and the terminals. 
     FIGS. 5-13 illustrate the method of the invention in fabricating electrical connector 1. First, cap 11 is threaded onto cable end 4a of cable 4 as shown in FIG. 5. The cable then is treated or prepared as shown in FIG. 6. Specifically, the conventional outer insulating cladding or jacket of the cable is removed at the distal end thereof to expose conductors 5. The insulation about the individual conductors is stripped to expose conductor ends 6. The inner shield of the cable is folded back over a distal end of the outer cladding of the cable, and an electrically conductive tape 9 is wrapped about the folded-back shield as shown in FIG. 6. 
     FIG. 7 shows the next step wherein the conductors are terminated to the terminals within plug body 2. Specifically, the stripped ends 6 of conductors 5 are soldered to tails 3a of the terminals. 
     Referring to FIGS. 8-11, conductive shield casing 8 is mounted to a longitudinal portion of the connector extending from plug body 2 to electrically conductive tape 9. The intermediate box-like section 8b of the shield casing includes upper and lower halves. The upper half is connected to head and tail sections 8a and 8c, respectively, by joint portions 10a and 10b. Referring to FIGS. 8 and 9, the upper half of the intermediate casing 8b is positioned, and tail section 8c is crimped about the taped end of the cable. Thereafter, and referring to FIGS. 10 and 11, the lower half of intermediate section 8b is positioned, thus enclosing the conductors and the terminations of the conductors with the terminals. 
     The next step of applying cylindrical sheath 12 is shown in FIGS. 12 and 13. It should be understood at this point that, although the sheath is generally rectangular in cross-section, it is considered cylindrical in a generic sense. The sheath is assembled by positioning the sheath in a rearward direction over the front end of plug body 2 until snap-latches 14 snappingly latch behind latch shoulders 16 as shown in FIG. 1 and as described above. Actually, snap-latches 14 are sandwiched between latch shoulders 16 and a step-like bent portion 15 of shield casing 8. Once the sheath is properly positioned and latched, cap 11 is moved forwardly to engage and seal the rear peripheral edge of the sheath and to close the interior cavity of the connector. 
     Lastly, dielectric boot 18 is overmolded about cable end 4a, about cap 11 and about the rear periphery of outer sheath 12 as seen best in FIG. 1. During the overmolding process, latch means 14 and 16 hold outer sheath 12 on shield casing 8, and cap 11 prevents the ingress of any overmolding material into the sheath and the interior of the connector. 
     As may be understood from the above, electrical connector 1 has no parts that must be precisely positioned onto cable 4 or cable end 4a and, therefore, the manufacturing efficiency will be increased, substantially reducing the possibility of making incomplete or defective products. The longitudinal section of cylindrical sheath 12 covering a substantial length of shield casing 8 is a prefabricated cylindrical hollow body which requires no complicated coupling means between the shield casing and the sheath other than the simple snap-latch means. Accordingly, the shield casing can be reduced to a simple structure permitting enlarging the inner space of the connector. Thus, tail 3a of the terminals are arranged laterally at increased pitch. The terminal tails are separated by partitions 7c, thereby eliminating the necessity of covering the tail and conductor connections with an insulating material such as tubes. The partitions facilitate the soldering process, and the tail and conductor terminations are reduced to a straight, shortest length. Thus, the tail and conductor terminations are free of wavy elongations as would result from insulating the tail and conductor terminations by tubes. Although conductors 5 are shown as being straight wires in FIGS. 1, 3, 6, 7, 8 and 9, simply for simplicity purposes in the drawings, each two conductors are, in fact, twisted to prevent signal interference between adjacent conductors 5. Only the conductors of short length close to terminal tails 3a in plug body 2 are untwisted and, therefore, no adverse effect can be caused because little or no interference would result at the untwisted location. 
     It will be understood that the invention may be embodied in other specific forms without departing from the spirit or central characteristics thereof. The present examples and embodiments, therefore, are to be considered in all respects as illustrative and not restrictive, and the invention is not to be limited to the details given herein.