High frequency electrical connector
An electrical connector for conducting high frequency signals includes a number of input and output terminals that are interconnected by a pair of metallic lead frames that are mounted on a dielectric spring block. The lead frames are identical to each other and comprise several flat elongated conductors, each conductor terminating in a spring contact at one end and an insulation-displacing connector at the other. The lead frames are mounted on top of each other and their conductors are all generally parallel and close to each other. Only three of the conductors of each lead frame are arranged to overlap each other; and this occurs in a designated crossover region without electrical contact being made because of a reentrant bend in the conductors in the crossover region. As a result, crosstalk between specific conductors can be reduced by judiciously choosing the location of the crossover and the particular crossover pattern.
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This invention relates to an electrical connector, and more particularly to an electrical connector having reduced crosstalk between wire-pairs.
BACKGROUND OF THE INVENTIONInformation flow has increased substantially in recent years, and networks have evolved to accommodate not only a greater number of users but also higher data rates. An example of a relatively high speed network is the subject of ANSI/IEEE Standard 802.5 which provides a description of the peer-to-peer protocol procedures that are defined for the transfer of information and control between any pair of Data Link Layer service access points on a 4 Mbit/s Local Area Network with token ring access. At such data rates, however, wiring paths themselves become antennae that both broadcast and receive electromagnetic radiation. This is a problem that is aggravated when station hardware requires multiple wire-pairs. Signal coupling (crosstalk) between different pairs of wires is a source of interference that degrades the ability to process incoming signals. This is manifested quantitatively as decreased signal-to-noise ratio and, ultimately, as increased error rate. Accordingly, crosstalk becomes an increasingly significant concern in electrical equipment design as the frequency of interfering signals is increased.
Crosstalk occurs not only in the cables that carry the data signals over long distances, but also in the connectors that are used to connect station hardware to the cables. ANSI/IEEE Standard 802.5 discloses a Medium Interface Connector having acceptable crosstalk rejection at the frequencies of interest. This Connector features four signal contacts with a ground contact, and is hermaphroditic in design so that two identical units will mate when oriented 180 degrees with respect to each other. This Connector is available as IBM Part No. 8310574 or as Anixter Part No. 075849. Crosstalk rejection appears to result from short connector paths, ground shields, and the selection of particular terminals for each wire-pair. As might be expected, such connector arrangements are relatively expensive and represent a departure from communication plugs and jacks such as specified in Subpart F of the FCC Part 68.500 Registration Rules and used in telecommunication applications.
For reasons of economy, convenience and standardization, it is desirable to extend the utility of the above-mentioned telecommunication plugs and jacks by using them at higher and higher data rates. Unfortunately, such plugs and jacks include up to eight wires that are close together and parallel—a condition that leads to excessive crosstalk, even over relatively short distances. Attempts to improve this condition are complicated by the fact that an assignment of particular wire-pairs to particular terminals already exists which is both standard and non-optimum. Indeed, in ANSI/EIA/TIA-568 standard, the terminal assignment for wire-pair 1 is straddled by the terminal assignment for wire-pair 2 or 3. If the electrical conductors that interconnect with these terminals are close together for any distance, as is the case in present designs, then crosstalk between these wire-pairs is particularly troublesome. Accordingly, it is desirable to reduce crosstalk in electrical connectors such as the plugs and jacks commonly used in telecommunication equipment.
SUMMARY OF THE INVENTIONIn accordance with the invention, an electrical connector for connecting an ordered array of input terminals to an ordered array of output terminals is improved. The connector includes at least four conductors that are spaced apart from each other and make electrical interconnection between the input and output terminals. The conductors are generally parallel to each other along a portion of the interconnection path and are arranged to change the relative ordering of terminals, between input and output, from the ordering that would result if all conductors were confined to the same plane.
In an illustrative embodiment of the invention, the input terminals of the electrical connector comprise insulation-displacing connectors, each having a pair of opposing contact fingers which functions to make electrical and mechanical connection to an insulated wire inserted therein. Further, the output terminals of the electrical connector comprise wire springs. Two lead frames, each comprising an array of conductors, are mounted on a dielectric block. Each conductor terminates, at one end, in a wire spring and, at the other end, in an insulation-displacing connector. Selected conductors of the lead frames cross over each other when they are mounted on the dielectric spring block, but are prevented from making electrical contact with each other at the point of crossover—one of the conductors includes an upward reentrant bend and the other includes a downward reentrant bend. Advantageously, the two lead frames are identical, but are reverse-mounted on the spring block in the left-to-right direction. The front side of the spring block includes a projection which fits into one end of a jack frame and interlocks therewith. Together, the spring block and jack frame comprise a standard modular jack of the type specified in the FCC Registration Rules.
The invention and its mode of operation will be more clearly understood from the following detailed description when read with the appended drawing in which:
Most communication systems transmit and receive electrical signals over wire-pairs rather than individual wires. Indeed, an electrical voltage is meaningless without a reference voltage—a person can't even get shocked unless part of his body is in contact with a reference voltage. Accordingly, the use of a pair of wires for electrical signal transmission is merely the practice of bringing along the reference voltage rather than relying on a local, fixed reference such as earth ground. Each wire in a wire-pair is capable of picking up electrical noise from noise sources such as lightning, radio and TV stations. However, noise pickup is more likely from nearby wires that run in the same general direction for long distances. This is known as crosstalk. Nevertheless, so long as each wire picks up the same noise, the voltage difference between the wires remains the same and the differential signal is unaffected. To assist each wire in picking up the same noise, the practice of twisting wire-pairs in various patterns emerged.
Terminal wiring assignments for modular plugs 50 and jacks 20 are specified in ANSI/EIA/TIA-568-1991 which is the Commercial Building Telecommunications Wiring Standard. This Standard associates individual wire-pairs with specific terminals for an 8-position, telecommunications outlet (T568B) in the manner shown by FIG. 2. The Standard even prescribes the color of each wire and Near End Crosstalk performance in the frequency range 1-16 MHz. While the color assignment does not lead to difficulties, the pair assignment does—particularly when high frequency signals are present on the wire-pairs. Consider, for example, the fact that wire-pair 3 straddles wire-pair 1, as illustrated in
The positioning of region II where the crossover occurs has been empirically determined. Distance “d,” indicated in
Referring again to
After the insulation-displacing connectors 323 of the lead frame are folded around each side wall 337 on opposite sides of the spring block, the spaces between the opposing contact fingers that form the insulation-displacing connectors are aligned with wire-receiving slots 333 of the spring block so that a wire may pass therebetween. Side walls 337 are substantially parallel to each other and perpendicular to the top surface 336 of the spring block. Furthermore, when cover 310 is joined with spring block 330, its slots 313 are aligned with the spaces between opposing contact fingers of the insulation-displacing connectors 323. As a result, the insulation-displacing connectors are sandwiched between the spring block and cover, and protected from the possibility of an inadvertent electrical short between adjacent connectors. After the cover is joined to the spring block, pins 334 in the spring block protrude through two of the holes 314 in the cover. These pins are heated and deformed, via ultrasonic welding, to permanently join t he cover to the spring block. Cover 310 includes four symmetrically-positioned holes 314 so that it can be interlocked with the spring block in either of two positions. Electrical connector 30 may now be inserted into jack frame 20 which includes latch 26 that cooperates with shoulder 316, molded into the top of cover 310, to interlock the two together. Note that jack frame 20 shows numbers 1 and 8 on its front face that establish a numbering convention for the positioning of terminals within the jack frame in accordance with option B of the ANSI/EIA/TIA-568 standard. Wiring labels 340 also includes number 1-8 that identify which slot 313 is interconnected to each specific terminal. Such labeling is particularly useful in the present invention where crossovers made by the conductors of lead frames 320-1, 320-2 change the relative ordering of wires from the ordering that would result if all the conductors were confined to the same plane.
Referring now to
The improvement offered by the present invention is dramatically illustrated in the frequency plots of FIG. 8 and FIG. 9.
Although a particular embodiment of the invention has been disclosed, various modifications are possible within the spirit and scope of the invention. In particular, it is understood that crossovers between different conductors will result in different amounts of crosstalk between the different wire-pairs. As illustrated, decreasing the amount of crosstalk between specific wire-pairs sometimes results in increasing the amount of crosstalk between other wire pairs. Furthermore, changing the location where crossover takes place influences the amount of crosstalk. These considerations are a matter of design choice. Crossover may be achieved using a double-sided printed wiring board and the use of metal staples or plated-through holes to achieve electrical connection. Finally, the principles of the present invention may be incorporated in numerous connectors including modular plugs and jacks as well as connecting blocks.
Claims
1. An electrical connector including a plurality of input terminals, a plurality of output terminals, and interconnection apparatus for electrically interconnecting the input and output terminals, the interconnection apparatus comprising at least four non-insulated conductors that are spaced apart from each other and mounted on a dielectric surface, said conductors being generally parallel to each other along a portion of the interconnection path between input and output terminals, the interconnection apparatus further including means for crossing the path of one of the non-insulated conductors over the path of another one of said conductors without making electrical contact therewith; whereby crosstalk of electrical signals between conductors in an electrical connector is reduced.
2. The electrical connector of claim 1 wherein each input terminal of the electrical connector comprises a pair of opposing contact fingers that function to make electrical and mechanical connection to a wire inserted therein.
3. The electrical connector of claim 1 wherein the output terminals of the electrical connector comprise resilient wires.
4. The electrical connector of claim 3 wherein the dielectric block surface includes a projection which fits into an opening in one side of a jack frame, and wherein the resilient wires wrap around the projection to form spring contacts for engaging an electrical plug inserted into an opening in the opposite side of the jack frame.
5. The electrical connector of claim 1 wherein the interconnection means apparatus includes first and second lead frames, each containing a plurality of the conductors that individually interconnect one predetermined input terminal with one predetermined output terminal, said lead frames being mounted on top of each other on the dielectric block surface.
6. The electrical connector of claim 5 wherein the first lead frame includes a conductor that crosses over the path of a conductor on the second lead frame, the conductor on the first lead frame including a reentrant bend at the point of crossover that precludes it from touching the conductor on the second lead frame.
7. The electrical connector of claim 6 wherein all of the conductors on the first lead frame includes reentrant bends along a line that extends from left-to-right across the lead frame.
8. The electrical connector of claim 7 wherein the first and second lead frames are identically constructed but are reverse-mounted on the dielectric block surface in the left-to-right direction.
9. In combination:
- a first metallic lead frame comprising a plurality of flat elongated conductors for communicating electrical signals, each of said conductors terminating at one end in a resilient wire and at the other end in an insulation-displacing connector;
- a second metallic lead frame comprising a plurality of flat elongated conductors for communicating electrical signals, each of said conductors terminating at one end in a resilient wire and at the other end in an insulation-displacing connector;
- a dielectric block having a top side surface with slots for receiving conductors therein, the first and second metallic lead frames being positioned on the top surface, at least one of the conductors of the first lead frame crossing over a conductor of the second lead frame; and
- means for precluding the conductors on the first and second lead frames that cross over each other from making electrical connection therewith.
10. In combination:
- a plurality of flat elongated conductors for conveying electrical signals along an interconnection path that extends from one end of the conductors to the other end thereof;
- a dielectric block including top and front side surfaces, the top surface having slots that are generally parallel to each other and receive the conductors therein; and
- means for changing the relative positioning of a first and second of the conductors so that along one portion of the path the first conductor is positioned on the right of the second conductor, and along another portion of the path the first conductor is positioned on the left of the second conductor; whereby crosstalk between conductors is reduced.
11. The combination of claim 10 wherein the front surface of the dielectric block includes a tongue-like projection around which the conductors are folded, said projection being shaped for insertion into an opening in a jack frame; whereby an electrical plug having reduced crosstalk is formed.
12. The combination of claim 11 further including a dielectric jack frame having front and back surfaces and an opening that extends therebetween, the opening in the front surface being adapted to receive an electrical plug inserted therein, and the opening in the back surface being adapted to receive the projection of the dielectric block; whereby an electrical jack having reduced crosstalk is formed.
13. An electrical jack comprising a conductor array, a spring block and a jack frame,
- the conductor array comprising:
- a plurality of generally co-planar electrical conductors, each being terminated in a resilient wire at one end and in an insulation-displacing connector at the other end;
- a first conductor in the array being positioned on the left side of a second conductor along one portion of a path that extends between their ends, and being positioned on the right side of the second conductor along another portion of the path;
- the spring block comprising:
- a dielectric structure including a tongue-like projection having top and bottom surfaces, the conductor array being positioned on the top surface of the dielectric structure with its resilient wires folded around the tongue-like projection forming spring contacts; and
- the jack frame comprising:
- a dielectric structure having front and back surfaces and an opening that extends therebetween, the opening in the front surface being adapted to receive an electrical plug inserted therein, and the opening in the back surface receiving the tongue-like projection in the spring block.
14. An electrical plug comprising a conductor array, a spring block and a cover,
- the conductor array comprising:
- a plurality of generally co-planar electrical conductors, each being terminated in a resilient wire at one end and in an insulation-displacing connector at the other end;
- a first conductor in the array being positioned on the left side of a second conductor along one portion of a path that extends between their ends, and being positioned on the right side of the second conductor along another portion of the path;
- the spring block comprising:
- a dielectric structure including a tongue-like projection having top and bottom surfaces, the conductor array being positioned on the top surface of the dielectric structure with its resilient wires folded around the tongue-like projection; and
- the cover comprising:
- a dielectric structure having left-side and right-side walls that are parallel to each other but perpendicular to a top surface that structurally joins the side walls, the cover being joined to the spring block in a manner such that the conductor array is captured between the cover and the spring block.
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Type: Grant
Filed: Nov 22, 2004
Date of Patent: May 4, 2010
Assignee: CommScope, Inc. of North America (Hickory, NC)
Inventors: W. John Denkmann (Carmel, IN), Willard A. Dix (Noblesville, IN), William T. Spitz (Indianapolis, IN)
Primary Examiner: Gary F. Paumen
Attorney: Myers Bigel Sibley & Sajovec, P.A.
Application Number: 10/994,928
International Classification: H01R 4/24 (20060101);