Claims
- 1. A tap connector for coaxial cable networks, comprising:
- a connector housing;
- first and second signal carrying contacts carried by said connector housing and adapted to be electrically connected to first and second conductors, respectively;
- normally closed switch means for electrically connecting said first and second signal carrying contacts for providing a first signal path between said first and second signal carrying contacts, said normally closed switch means including a movable switch arm attached to each of said first and second signal carrying contacts and adapted to normally engage the other of said signal carrying contacts for normally providing said first signal path between said first and second signal carrying contacts;
- a third grounding contact carried by said housing and adapted to be connected to conductive sheaths of one or both of said first and second conductors; and
- receiving means on said housing for receiving a mating connector, whereby said first, second and third contacts are engaged by terminals on said mating connector when said mating connector is received by said receiving means for providing electrical connection of said first and second signal carrying contacts and of said third grounding contact with said terminals on said mating connector, and for establishing a second signal path between said first and second signal carrying contacts through said mating connector, said movable switch arms being adapted to be displaced from the other of said signal carrying contacts in a direction generally parallel to the direction of movement of said mating connector by cam surfaces on said mating connector during mating of said mating connector with said tap connector to open said normally closed switch means for interrupting said first signal path whereby only said second signal path through said mating connector is provided between said first and second signal carrying contacts when said mating connector is received by said receiving means.
- 2. The tap connector of claim 1 wherein said normally closed switch means further includes a stationary switch arm attached to each of said first and second signal carrying contacts and adapted to normally be engaged by the movable switch arm attached to the other signal carrying contact for providing said first signal path between said first and second signal carrying contacts.
- 3. The tap connector of claim 1 wherein said first and second signal carrying contacts are substantially identical and are interchangeable in said tap connector.
- 4. The tap connector of claim 1 wherein said first and second signal carrying contacts comprise insulation displacement contacts.
- 5. The tap connector of claim 1 and further including first and second fittings adapted to be attached to said housing for attaching said first and second conductors to said tap connector.
- 6. The tap connector of claim 5 wherein said tap connector is adapted to connect first and second coaxial cables of said cable network, said first and second conductors comprising signal carrying conductors of said first and second cables, respectively, and wherein said first and second fittings are adapted to attach said first and second cables to said tap connector.
- 7. The tap connector of claim 5 wherein said tap connector is adapted to terminate said cable network said first conductor comprises a signal carrying conductor of an electrical cable and said second conductor comprises a conductive wire terminated by a resistor, said first fitting being adapted to attach said electrical cable to said tap connector and said second fitting being adapted to attach said conductive wire terminated by said resistor to said tap connector.
- 8. The tap connector of claim 7 wherein said conductive wire and said resistor are supported by said second fitting and wherein said second signal carrying contact is adapted to be connected to said conductive wire to terminate said cable network.
- 9. The tap connector of claim 8 wherein said second fitting is threadedly attached to said housing.
- 10. In an electrical connector for an electrical cable having a conductive sheath surrounding at least one electrical conductor, the connector comprising, first and second clamping members having corresponding passageways, the clamping members having corresponding sheath engaging surfaces, the clamping members being constructed for attachment to each other with the passageways aligned for receiving at least one conductor of an electrical cable, and with the sheath engaging surfaces opposing each other for clamping a conductive sheath of an electrical cable, which conductive sheath extends radially relative to an axis of the cable, the improvement comprising;
- the sheath engaging surfaces are substantially disk shaped with at least one of the sheath engaging surfaces being constructed to bow outwardly toward the other and to flatten upon clamping a conductive sheath of an electrical cable and to recover by spring action to maintain a conductive sheath clamped by the sheath engaging surfaces notwithstanding limited movement apart of the sheath engaging surfaces.
- 11. In an electrical connector as recited in claim 10, the improvement further comprising;
- a housing of the second clamping member, and conductive means in said housing for electrical connection to a corresponding electrical conductor of an electrical cable.
- 12. In an electrical connector as recited in claim 10, the improvement further comprising;
- the sheath engaging surface of the first clamping member is on an insulative portion of said first clamping member.
- 13. In an electrical connector as recited in claim 12 wherein said first clamping member includes an annular cavity extending inwardly from said sheath engaging surface thereof for receiving excess portions of said radially extending conductive sheath when said conductive sheath is clamped by said sheath engaging surfaces.
- 14. In an electrical connector as recited in claim 12, the improvement further comprising; the first clamping member includes an eyelet extending into the passageway of the first clamping member, said eyelet including a radially extending flange portion for securing said conductive sheath between said sheath engaging surface of said first clamping member and said eyelet for providing strain relief for said electrical cable.
- 15. In an electrical connector as recited in claim 10, the improvement further comprising;
- said outwardly bowed sheath engaging surface is radially segmented for further maintaining a conductive sheath clamped by the sheath engaging surfaces notwithstanding limited movement apart of the sheath engaging surfaces.
BACKGROUND OF THE INVENTION
This application is a continuation in part of application Ser. No. 07/004,512, filed Jan. 20, 1987, now U.S. Pat. No. 4,744,774, and a continuation in part of application Ser. No. 07/013,748, filed Feb. 12, 1987, now U.S. Pat. No. 4,744,775.
The present invention relates generally to the field of electrical connectors and, more particularly, to a tap connector assembly for coaxial cable networks.
One expanding use for electrical tap connectors is in the field of premises wiring. Premises wiring typically carries voice, electronic data, and/or electrical power over one or more electrical conductors and/or one or more optical fibers gathered together in a communications cable network. Workstations situated at various locations in the same building or in separate buildings are linked to the cable network by tap connectors; and the network, in turn, links the workstations to one another to receive or transmit data carried by the network.
The communications cable may take various forms. For example, the cable may comprise a twisted pair cable containing insulated wires that are spirally twisted together in pairs. Alternatively, the cable may comprise a coaxial cable containing one or more insulated conductors surrounded by a cylindrical, conductive sheath Optical fiber cables may also contain a sheath surrounding the optical fibers within the cable to provide the cable with physical strength and to provide a shield to protect the fibers. Such a sheath may be electrically conductive to provide for a ground electrical potential along the sheath and along the length of the cable.
Tap connectors for coaxial cable networks were frequently relatively difficult to install and required special tools and skills for proper installation. In addition, many coaxial tap connectors were not effective in maintaining the integrity of the overall network when the connectors were not in use or when external apparatus was being plugged into or disconnected from the network. Furthermore, many coaxial tap connectors were not fully satisfactory with respect to providing reliable electrical connection between the cylindrical conductive sheath of the communications cable and the connector. There is, in fact, a large demand generally for electrical connectors which are capable of effectively clamping the conductive sheath of a communications cable.
U.S. Pat. No. 4,126,372 discloses a known electrical connector that comprises a first cone shaped clamping jaw member having an axial passage for receipt of a coaxial cable. The clamping jaw member has a truncated conical end that tunnels concentrically under a cylindrical conductive sheath, also referred to as an outer conductor, of a coaxial cable. A second clamping jaw member is slidable over the conductive sheath. The first and second clamping jaw members are electrically conductive and clamp the conductive sheath therebetween to establish an electrical connection of the conductive sheath to the connector.
U.S. Pat. No 4,126,372 discloses that the cylindrical conductive sheath of a coaxial cable may be flared outwardly or folded back in order to permit two conductive clamping jaw members to clamp the sheath therebetween. The clamping jaw members are formed with inclined wedge shapes which conform to either the flared or folded back shape of the sheath.
The conductive clamping jaw members of the apparatus disclosed in U.S. Pat. No. 4,126,372 are fabricated from thick metal parts having sufficient mass to withstand the clamping forces The members are fabricated by manufacturing procedures which involve separately machining the members. Machining operations are capable of producing parts having precise dimensions and tolerances. However, the rate at which the parts are produced is slow, and the cost of their manufacture is relatively high. Machining operations, accordingly, are only suitable for producing parts in small quantities or when the need for high precision justifies a more costly manufacturing technique.
The large demand for tap connectors and for other connectors which are capable of clamping the outer conductive sheath of a communications cable has spurred efforts to reduce the cost of such connectors, either by improving manufacturing techniques or by redesigning the connectors to eliminate the need for costly manufacturing techniques. A further reduction in cost can be realized if the connectors are designed for field application, defined as assembly of the connectors to cables at locations where the cables are installed for use. An even further cost reduction can be obtained if the connectors are capable of being assembled to cables by untrained workers without the need for special tools.
Connectors having parts fabricated from stamped and formed metal strip are significantly less costly than connectors having machined parts. An electrical connector having clamping jaws fabricated with stamped and formed metal strip and being sufficiently rugged to withstand the clamping forces applied by the jaws to the outer conductive sheath of a cable would be a highly desirable product.
According to one aspect of the present invention, a tap connector assembly for electrical cable networks is provided which comprises a tap connector connected to the cable network, and a mating connector mateable with the tap connector to connect external apparatus into the cable network.
The tap connector includes a connector housing; first and second signal carrying contacts carried by the housing and adapted to be electrically connected to first and second conductors, respectively; normally closed switch means for electrically connecting the first and second signal carrying contacts for providing a first signal path between the first and second signal carrying contacts, the normally closed switch means including a movable switch arm attached to each of the first and second signal carrying contacts and adapted to normally engage the other of the signal carrying contacts for normally providing the first signal path between the first and second signal carrying contacts; a third grounding contact carried by the housing and adapted to be connected to conductive sheaths of one or both of the first and second conductors; and receiving means on the housing for receiving a mating connector, whereby the first, second, and third contacts are engaged by terminals on the mating connector when the mating connector is received by the receiving means for providing electrical connection of the first and second signal carrying contacts and of the third grounding contact with the terminals on the mating connector, and for establishing a second signal path between the first and second signal carrying contacts through the mating connector, the movable switch arms being adapted to be displaced from the other of the signal carrying contacts in a direction generally parallel to the direction of movement of the mating connector by cam surfaces on the mating connector during mating of the connector with the tap connector to open the normally closed switch means for interrupting the first signal path whereby only the second signal path through the mating connector is provided between the first and second signal carrying contacts when the mating connector is received by the receiving means.
With the tap connector of the invention, the normally closed switch means provides a first signal path between the first and second signal carrying contacts and between the first and second conductors connected thereto to maintain the integrity of the cable network when the tap connector is not in use. When the mating connector is mated with the tap connector, however, a second signal path is established between the first and second signal carrying contacts through the mating connector; and the normally closed switch means is opened to interrupt the first signal path, thus providing a series connection with the cable network of apparatus connected by the mating connector.
Preferably, the tap connector comprises a receptacle tap connector; the mating connector comprises a plug connector; and the mating connector receiving means comprises a cavity in the receptacle tap connector for receiving the plug connector. During mating of the plug and receptacle connectors, first and second terminals in the plug connector engage the first and second signal carrying contacts in the receptacle tap connector, momentarily creating a dual signal path between the first and second signal carrying contacts. Further insertion of the plug connector into the cavity in the receptacle tap connector causes the cam surfaces on the plug connector to engage the movable switch arms of each signal carrying contact, separating them from the opposite signal carrying contact leaving only the second signal path through the plug connector connected in the network. With the connector assembly of the invention, accordingly, the first signal path is not broken until after the second signal path is established. Similarly, when the plug connector is disconnected from the receptacle tap connector, the cam surfaces on the plug connector release the movable switch arms, allowing the switch means to close and reestablish the first signal path prior to disconnection of the second signal path. Thus, with the present invention, network integrity is maintained at all times.
According to a presently preferred embodiment of the invention, the first and second signal carrying contacts are identical and interchangeable in the connector permitting a reduction in both inventory requirements and manufacturing costs. In addition, the movable switch arms are designed to be moved by the cam surfaces on the plug connector in a direction substantially parallel to the direction of movement of the plug connector for more reliable operation of the normally closed switch means when the plug connector is mated with or disconnected from the tap connector. Also, the inclusion of two movable switch arms in the normally closed switch means provides a redundancy in the switch means for even greater operating reliability.
The receptacle tap connector of the invention is designed to be easily assembled and incorporated into a cable network without specialized tools or skills. In particular, the receptacle tap connector includes a plastic housing, a grounding contact supported by the housing, first and second fitting assemblies for attaching the first and second conductors to opposite ends of the housing, and a signal carrying contact assembly containing first and second insulation displacement, signal carrying contacts and the switch means. Usually, the tap connector will be used to connect first and second coaxial electrical cables into the cable network and the first and second fitting assemblies each includes structure for defining a first sheath engaging or clamping surface, and the grounding contact includes a pair of disk shaped portions defining second sheath engaging or clamping surfaces.
To assemble the receptacle tap connector to a cable network, the first and second cables are extended through central apertures in the first and second fitting assemblies, respectively Exposed portions of the outer conductive sheaths of the first and second cables are then fanned out against the first sheath engaging surfaces of the first and second fitting assemblies. The fitting assemblies are then attached to the housing to clamp the conductive sheaths of the first and second cables between the first clamping surfaces on the fitting assemblies and the second clamping surfaces on the grounding contact to electrically connect the conductive sheaths of the first and second cables to the grounding contact. The signal carrying conductors of the first and second cables, surrounded by inner dielectric sheaths, extend into the housing when the fittings are attached to the housing. The signal carrying contact assembly is then mounted to the housing, causing the first and second insulation displacement, signal carrying contacts to pierce the inner dielectric sheaths of the cables to electrically connect the contacts to the signal carrying conductors of the cables and complete the assembly.
In another application, the tap connector is used to terminate a cable network, and in such application, the second fitting assembly comprises a network terminator containing a conductor attached to a resistor for preventing unwanted reflections back into the circuit.
An important aspect of the tap connector assembly of the present invention is the inclusion of clamping means which effectively secures the outer conductive sheath of a communications cable to the connector for establishing a reliable electrical connection between the outer conductive sheath and the connector. In accordance with this aspect of the invention, an electrical connector for an electrical cable having a conductive sheath surrounding at least one electrical conductor is provided which comprises, first and second clamping members having corresponding passageways, the clamping members having corresponding sheath engaging surfaces, the clamping members being constructed for attachment to each other with the passageways aligned for receiving at least one conductor of an electrical cable, and with the sheath engaging surfaces opposing each other for clamping a conductive sheath of an electrical cable, which conductive sheath extends radially relative to an axis of the cable, the improvement comprising wherein the sheath engaging surfaces are substantially disk shaped with at least one of the sheath engaging surfaces being constructed to bow outwardly toward the other and to flatten upon clamping a conductive sheath of an electrical cable and to recover by spring action to maintain a conductive sheath clamped by the sheath engaging surfaces notwithstanding limited movement apart of the sheath engaging surfaces.
According to a presently preferred embodiment, the first clamping member comprises an insulative fitting having a radial surface which defines the first sheath engaging surface, and the second clamping member comprises an electrically conductive grounding contact in a connector housing. A cable having a conductive outer sheath and one or more center conductors is extended through the passageway in the fitting, and an exposed portion of the outer, conductive sheath of the cable is flared outwardly at substantially right angles to the axis of the cable so as to be positioned between the sheath engaging surfaces of the fitting and the grounding contact. Thereafter, when the first and second clamping members are clamped together, for example, by threading the fitting onto the connector housing, the exposed conductive sheath will be firmly clamped between the two sheath engaging surfaces to establish electrical contact between the conductive sheath of the cable and the grounding contact in the connector. The one or more center conductors of the cable continue through the passageway in the grounding contact to be connected to center conductor connection means such as electrical contact means in the connector.
The sheath engaging surface of the grounding contact is bowed outwardly toward the sheath engaging surface on the fitting such that it is able to collapse in a fashion similar to a Belleville washer, recovering as necessary through spring action to compensate for movement of the fitting relative to the housing as a result of plastic creep. The bowed, sheath engaging surface is also preferably of radially segmented construction to further help overcome any tendency of plastic creep between the housing and the fitting.
In general, the present invention provides an electrical connector having clamping means for reliably securing the outer conductive sheath of a cable to the connector that can be manufactured in large quantities at low cost. Assembly of the connector and of the cable to the connector can be made in the factory or in the field by unskilled personnel using ordinary tools such as a knife and a pair of pliers. The fitting can be attached to the housing by hand without the use of tools.
Further features and advantages of the invention will become apparent hereinafter in conjunction with the following detailed description of a presently preferred embodiment.
US Referenced Citations (4)
Continuation in Parts (1)
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Number |
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4512 |
Jan 1987 |
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Patent Grant
4795356
