Coaxial cable insulation displacement connector

A right-angle coaxial cable connector has an inner cable stop for positioning an end of a coaxial cable in a specific location within an electrically conductive connector housing. A terminal device of the connector includes a center contact terminal with insulation displacement blades on one end. A dielectric member is sandwiched between the center contact terminal and an outer electrical contact. The cable stop surface may be a direct projection from the housing or an extension of the dielectric member. The projection or dielectric member electrically isolates a conductive core of the cable from the connector housing. Full insertion of the terminal device or a part of the terminal device into the connector housing causes the blades to cut through insulation of the cable and electrically connect the conductive core of the cable with the center contact terminal. The structure of the connector housing and the assembly process enable inspection of the cable end location within the housing prior to termination of the cable. A ferrule is used to secure the cable to the housing after confirmation of the location. The outer electrical contact of the terminal device is electrically connected to an outer conductive sheath of the cable through the connector housing when the ferrule is crimped on the housing around the sheath.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention is directed in general to an angled coaxial cable connector and more specifically to such a connector that makes use of an insulation displacement termination method to minimize assembly time and connector size.

2. Discussion of Related Art

Coaxial cable connectors often have a right-angle, or some other angle, design to facilitate electrical engagement with connection ports or printed circuit boards. This can eliminate the need to significantly bend the cable, and thereby possibly damage the connection between the connector and cable, when making the electrical engagement. Typical right-angle coaxial cable connectors use traditional methods of terminating the cable in the connector such as soldering and crimping. Both have advantages and disadvantages. In the soldering method, the size of the connector can be relatively small because the cable is brought in perpendicular to an axis of the interface between two contact sections. However, this procedure is time consuming and often hazardous. The crimping method is faster and non-hazardous in comparison to the soldering method. There are two types of crimp configurations. One requires two contacts, resulting in increased component count. The other requires only one contact, but the cable has to be bent, so this method requires a longer connector length due to the bend radius of the cable.

One way of doing away with the need for two separate terminals crimped or soldered together to provide the right angle turn within the connector is disclosed in co-pending U.S. patent application Ser. No. 11/016,919, filed Dec. 21, 2004. A connector assembly has first and second main components. A terminal crimped on an end of a coaxial cable is inserted through the second component and secured in the first component when the two components are in a straight or in-line configuration. The cable is secured to the second component. Then the second component is rotated relative to the first component to bend the cable and transform the assembly into a right-angle connector.

U.S. Pat. No. 4,632,486 provides an example of how insulation displacement terminals have been used in coaxial cable connectors. A ribbon-type coaxial cable has its outer jacket and each conductive sheath stripped back from the inner insulation layer and signal wire. The cable is inserted into and secured by adhesive within a first housing part of insulating material. A second, separate housing part also made of insulating material contains female terminals having insulation displacement contact portions at one end. The insulation displacement contact portions protrude from the second housing part. When the two housing parts are guided together the insulation displacement contact portions cut through the inner insulation layers to contact the signal wires and electrically connect the signal wires with the female terminals. While the method disclosed in this patent may provide a solution for terminating ribbon-type coaxial cables, it requires a large, two-piece connector and does not address problems associated with connectors requiring center contact terminals with concentric outer terminal sockets. A smaller size, lower component count connector with a fast termination method would provide a significant improvement to these existing types of connectors.

SUMMARY OF THE INVENTION

Accordingly, it is an object of this invention to provide a right-angle coaxial cable connector that is as small as a contact interface and cable size will allow.

Another object of the invention is to eliminate the need for soldering and crimping methods for terminating the inner conductor of the cable.

A further object of the invention is to minimize the number of connector components while incorporating a fast termination method.

In carrying out this invention in the illustrative embodiment thereof, an electrically conductive, one-piece connector housing has a first, main cylindrical section for receiving a terminal device and a second, barrel section for receiving an end of a coaxial cable. The sections have intersecting interiors. The coaxial cable end is stripped to expose the inner insulation layer and a cut-back part of the outer conductive sheath is flared outward. The stripped end of the cable is inserted through the barrel section into the first section. A cable stop positions the cable end in a specific, proper location for electrical connection with the terminal device. This location can be visually confirmed by looking into the first section. Then a ferrule is used to crimp the flared sheath around the barrel section, securing the cable to the connector housing.

The cable stop can be provided by a projection within the first housing section against which the insulating layer of the cable end abuts. The projection creates a space between an inner conductive core or signal wire of the cable end and the conductive housing, electrically separating the core of the cable from the housing. Alternatively, the cable stop can be provided as an extension of a dielectric member associated with the terminal device.

The terminal device comprises an inner contact terminal having a female terminal part at one end and insulation displacement blades at an opposite end. The inner terminal is held within the dielectric member. An outer socket or contact is fit around the dielectric member. In one possible assembly process, the inner terminal, dielectric member and outer contact are secured together in fixed position. Press-fitting the outer contact into the first section of the connector housing causes the insulation blades on the inner terminal to cut through the insulation layer of the cable and physically and electrically contact the core.

In another possible assembly process, the dielectric member with the extension for providing a cable stop is press-fit into the first housing section before insertion of the cable end. The inner terminal is movable within the dielectric member, and after the cable end is positioned in the correct location the inner terminal with the insulation displacement blades is forced into electrical contact with the cable core. The outer contact is separately press-fit into the first housing section, either after the electrical connection is made or simultaneously with a single tool stroke acting on both the outer contact and inner terminal.

The invention enables the size of the connector to be reduced. It allows use of an insulation displacement termination method for faster termination of coaxial cables. There is a reduction in the number of components and the assembly process can be automated. These advantages combine to result in a low-cost and easier to assemble connector.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Referring now toFIG. 1, a coaxial cable12has an end14prepared for termination to a right angle coaxial cable connector according to the current invention. An outer insulative jacket16of the cable is stripped back a predetermined distance and then an outer conductive sheath or braid18is exposed and cut back a second, specific distance from the end14. An inner insulation layer20and center conductive core22are left undisturbed. A ferrule24, fashioned from a ductile, electrically conductive material such as brass, is slid over the cable end to surround the outer jacket16adjacent the cable end. Then the braid18is flared outward.

A connector body or housing30according to the present invention is shown inFIG. 2. The housing may be die-cast from an electrically conductive metal or material such as zinc or a zinc-aluminum alloy. The connector housing30has a generally hollow, cylindrical, first main section32with a first, open, terminal mating end34and a second, cable receiving end36. A relatively smaller second, barrel section38extends at an angle from the main section32adjacent the cable receiving end36. The angle is depicted as being a right angle, but could be a different angle depending on the requirements of the connector environment. The barrel section38tapers to a free end40distal from the main section32. The barrel section has a central, internal passage42leading to an interior of the main section.

The interior of the main section32comprises a series of chambers decreasing in internal diameter from the terminal mating end34to adjacent the cable receiving end36. A first chamber44extends from the terminal mating end34back partially along the main section to an inclined step or ledge46. A second chamber48stretches along the main section from the first chamber to an inclined step50. A third chamber52extends from the step50along the main section to a first radial wall54. A fourth chamber56continues back along the main section to a second radial wall58. A dome-shaped depression60is formed in the radial wall58adjacent the second end of the main section32.

The fourth chamber56intersects with the internal passage42through the barrel section38of the housing30at an opening62in an annular wall64of the chamber. On an opposite side of the fourth chamber from the opening62, there is a cable stop surface formed by a protruding projection66at the junction of the annular wall64and the radial wall58.

The purpose or function of the projection66is depicted inFIG. 3. The internal diameter of the passage42through the barrel section38is sized to snugly receive the exposed inner insulation layer20of the coaxial cable end14. The insulation layer at the end14engages the projection66as the flared conductive braid18wraps around the barrel section38and abuts against the main section32of the housing. The projection66acts as a cable stop, and provides a gap or space68between the conductive core22of the cable and the annular wall64of the fourth chamber56. In other words, the projection66prevents electrical contact between the core22and the housing30, guarding against electrical shorting of the core22. The projection is aligned or in-line with the chambers and open end34of the first housing section. Therefore, an assembler can look through the chambers from the terminal mating end34to inspect the position of the cable and make sure the inner insulation layer is against the projection66.

As shown inFIG. 4, after the coaxial cable end is pressed against the projection66, the ferrule24is slid over the braid18and connector housing barrel section38until it engages the main section32and captures the conductive braid between the ferrule and barrel section. The ferrule is then crimped around the braid and barrel section, ensuring good electrical contact between the braid and conductive connector housing30. This secures the coaxial cable12to the connector housing30with the braid18in electrical contact with the housing and the core22of the cable electrically isolated from the housing by the air in space68within the chamber56.

The different cross-section views ofFIGS. 5 and 6illustrate that the housing30includes a guide slot69extending along the inner walls of chambers48and52. These Figures also illustrate a terminal device70prior to insertion into the main section32of the connector housing30and assembly with the housing and coaxial cable end14. The terminal device70comprises an inner center contact terminal72, an outer contact terminal74, and a dielectric insert or member76sandwiched between the terminals and electrically isolating them from each other.

The inner center contact terminal72has a first end80in the form of a female terminal part82and a second part or end84comprising insulation displacement surfaces or blades86. The terminal72is illustrated as being stamped or otherwise manufactured in one piece and is made from an electrically conductive metal such as brass or stainless steel. The female terminal part82could alternatively be formed as a male terminal, depending on the type of terminal the connector housing30is meant to mate with. A center part or portion87of the terminal72has longitudinally spaced sets of resilient retention barbs88, one set at a forward end adjacent the female terminal part82and another set at a rearward end adjacent the blades86, for securing the terminal in the dielectric member76. The retention barbs are depicted as angled cut-outs from the center portion87. The center portion87also includes an orientation projection89adjacent the barbs at the forward end.

The dielectric insert or member76may be made from a material such as Nylon, Teflon, polybutylene-terephalate or any of a variety of extruded plastics. It comprises a first cylindrical segment90, a second cylindrical segment92larger in outer diameter but shorter in length than the first cylindrical segment, and a short lip or rim element94on the opposite side of the second segment92from the first segment90. The rim element94has a rounded or beveled edge95. A ledge96is formed where the first segment90joins the second segment92, and a radial stop surface98is formed at the juncture of the rim element94and second segment92. As best seen inFIG. 6, an outer surface100of the second segment92has a groove or channel102along its length.

The dielectric member76has a central passage104passing through it, with a narrower inner portion106. Each end of the narrower portion106provides a stop surface108against which the retention barbs88of the center contact terminal72catch when the terminal72is pushed into the dielectric member. A slot109in an inner wall of the narrower passage portion106interacts with the orientation projection89on the center portion87of the terminal to orient and guide the terminal into the proper position. In the fully inserted, locked position, the female terminal part82extends through the first segment90of the dielectric member76, the center portion87of the terminal is clamped by the retention barbs88within the narrower portion106of the passage through the member, and the insulation displacement blades86extend out of the rim segment94of the member.

The outer female socket or contact74is constructed to accept a standard male connector (not shown) for mating with the female terminal72. Like the terminal72, it may be stamped and bent or otherwise manufactured in one piece from a conductive metal such as brass or stainless steel. The contact74has a ring element110with an inner annular surface112and an outer surface114. A first end116of the ring element is sized to receive the dielectric member76. Spring fingers118extend from the ring element110for receiving the male connector through a second end120.

The outer surface114of the ring element110adjacent the first end116has a short guide protuberance122. The inner surface112of the ring element has a longitudinal rib (not shown in order to illustrate the channel102on the outer surface100of the second segment92of the dielectric member76in cross-section) and tabs124bent inward into an interior of the ring element. The tabs124are spaced from the first end116of the ring element110at a distance equal to the length of the second segment92of the dielectric member.

The dielectric member76(with the secured inner contact terminal72) is inserted through the first end116of the outer contact74. The channel102is aligned with the rib on the inner surface of the ring element110to orientate the insert and prevent rotation of the member relative to the outer contact. The outer surface100of the second segment92of the member is press-fit into the ring element until the ledge96abuts against the bent tabs124.

The assembly of the terminal device70with the connector housing30is done in an automated process. A tool inserts the ring element110of the outer contact74through the first chamber44after aligning the guide protuberance122with the slot69(as shown inFIGS. 7 and 8) in chambers48and52. The guide protuberance is received by the slot and then, as illustrated inFIGS. 9 and 10, the ring element is press-fit into the third chamber52. Simultaneously, the rim element94of the dielectric member76is guided into the fourth chamber56and the insulation displacement blades86of the inner terminal72cut into the inner insulation layer20of the cable end14and make mechanical and electrical contact with the center conductive core22of the cable12. The second radial wall58in the fourth chamber56provides a cable support area that holds the cable end14against deflection as the blades slice into the cable. The dome-shaped depression60provides a clearance area for the blades, ensuring the blades don't contact the connector housing30and short the connection between the core and inner contact terminal. The perspective and cut-away views ofFIGS. 11 and 12, respectively, show the completed connector assembly and mated cable.

FIGS. 13–20illustrate a second embodiment of the invention. In this embodiment, the projection66forming the cable stop surface in the fourth chamber56of the main connector section32is replaced by an extension or extended wall or portion130of the rim element94of the dielectric member76. The resistance to electrical shorting depends on the dielectric constant of the material. The air in the space provided by the projection66in the first embodiment has a smaller dielectric constant and therefore less resistance to shorting than the plastic of the dielectric member. A higher dielectric constant is needed when a higher dielectric withstanding voltage (DWV) is required to prevent electrical arcing. While this embodiment has the advantage of giving the connector a higher DWV, some modifications to the connector housing, dielectric member and outer contact structure as well as to the assembly process are needed. The same reference numbers are used to refer to components similar to those in the first embodiment.

Referring toFIGS. 13 and 14, the dielectric member76is first assembled with the inner center contact terminal72. A narrower inner portion132of the central passage104through the member is shortened in this embodiment such that it is not clamped between the sets of retention barbs88of the terminal72. Initially, the set of retention barbs88adjacent the insulation displacement blades86contact the associated stop surface108of the member. The set of retention barbs88adjacent the female terminal part82of the terminal remain spaced from the associated stop surface108on the opposite end of the shortened narrower inner portion such that the first end80of the terminal protrudes from the first segment90of the member. This initial position keeps the blades86mostly within the confines of the rim element94of the member.

The main section32of the connector housing is modified to have a first chamber134adjacent the terminal mating end34, a second, intermediate chamber136with a longitudinal slot138in its inner wall, and a third chamber140intersecting with the internal passage42through the barrel section38of the housing. The third chamber140is sized such that the rim segment94and its extended portion130of the dielectric member76can be press-fit into the chamber140, with the extended portion130located across the chamber from the opening62of the passage42. Recesses142are formed in a top or end wall144of the third chamber140directly aligned with the blades86of the terminal72.

The connector housing main section32also includes an outer indentation146, allowing the ferrule24to be brought in closer to a longitudinal center-line of the main section and thereby enabling the barrel section38to be shorter. This reduces the overall length of the connector. As illustrated inFIGS. 14 and 15, the main section is also modified to include a window148. The window148allows viewing of the cable end14and the extended portion130of the rim element94of the dielectric member76within the third chamber140prior to assembly of the outer female socket or contact74with the connector housing. The window is needed to inspect the positions of the extended dielectric portion130and the cable end12because, since the dielectric member76must now be inserted into the connector housing before the cable end, the final position of the cable end can no longer be viewed through the chambers of the main section32.

The dielectric member76with the inner terminal72in the initial position within the member is first inserted into the main section32of the connector housing30. The rim element94with its extended portion130is press-fit into the third chamber140, holding the dielectric insert within the housing. The coaxial cable end14is then pushed through the barrel section38of the housing until it crosses the chamber140in the main section and abuts against the extended portion130. The assembler then looks through the window148to make sure the cable end is contacting the dielectric member and electrically isolating the cable core22from the connector housing. If the inspection confirms this condition, the ferrule24is crimped over the braid18onto the barrel section to secure the cable to the connector housing in the correct position.

The outer female socket or contact74is generally of the same construction as in the first embodiment except that it includes a relatively short appendage150extending from the first end116of the ring element110. The appendage150is positioned to close or cover the window148when the outer contact74is press-fit into the intermediate chamber136of the main section32after the dielectric member and cable end are assembled in the housing30. The guide protuberance122on the outer contact is aligned with the slot138and the tool forces the ring element110of the outer contact into the intermediate chamber. The appendage150covers the window148internally as best illustrated inFIGS. 17 and 19. This provides the connector with good shielding effectiveness for the cable termination.

In the last assembly step, the inner center contact terminal72is pressed toward the cable end14by exerting force on a push area152within the female terminal part82. The insulation displacement blades86cut through the insulation layer20of the cable and make electrical contact with the core22as the set of retention barbs88adjacent the female terminal part abut against the associated stop surface108formed by the shortened narrower inner portion132of the passage through the dielectric member. This completed assembly is shown inFIGS. 16 and 17. The end wall144of the third chamber140acts as a support surface to prevent deflection of the cable end. The recesses142in the end wall144ensure the blades86do not contact the connector housing.

In one alternative assembly process, the inner center contact terminal72can be forced to terminate the cable prior to press-fitting the outer contact into the main section of the housing. This would have the benefit of allowing viewing of the cable termination by the blades86before the window is covered by the outer contact appendage150.

FIG. 18shows another alternative assembly process, wherein the outer contact74is inserted only to a pre-set position. The appendage150does not block the window148, and the blades86of the inner terminal72do not cut into the cable end14. The advantage of this process arises when the assembly of the connector and the termination of the cable are done at different facilities. The pre-assembled connector can be shipped as one piece. A component (the outer contact) does not have to be shipped separately. At the final facility, the cable end14can be inserted in the connector housing30, its position can be inspected through the window148, and a single stroke of the tool can press the outer contact74into the position wherein the appendage150covers the window while simultaneously forcing the blades86of the inner terminal72into electrical contact with the coaxial cable core22.

FIGS. 19 and 20illustrate the completed connector assembly. These views are closer to the actual size of the connector assembly. The assembly in use is received in a plastic, electrically non-conductive outer housing. The ferrule24and the outer female socket or contact74act as electrical grounds and shields for the inner center contact terminal72and the terminated end14of the coaxial cable12.

Since minor changes and modifications varied to fit particular operating requirements and environments will be understood by those skilled in the art, this invention is not considered limited to the specific examples chosen for purposes of illustration. The invention is meant to include all changes and modifications which do not constitute a departure from the true spirit and scope of this invention as claimed in the following claims and as represented by reasonable equivalents to the claimed elements.