US 3200355 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
Aug. 10, 1965 V T. E. DAHLEN 3,200,355
ELECTRICAL CONNECTOR HAVING RF FILTER Filed Nov. 24. 1961 2 Sheets-Sheet 1 Z /EODOQE E: Dfif/LEN I N VE N TOR.
United States Patent ELlEtZTRlCAL CUNNECTUR HAVING RF FILTER Theodore E. Dahlen, La Puente, Caiif., assignor, by mesne assignments, to international Telephone and Telegraph Corporation, New York, N .Y., a corporation of Maryland Filed Nov. 24, 1961, Ser. No. 154,807 6 (Zlaims. (Cl. 333-49) The present invention relates to electrical connectors wherein one or more contact terminals are mounted in one connector member and complementary contact terminals are mounted in another connector member, the cor1- tact terminals mating to provide one or more electrical circuits upon interengagement of the two connector members. The invention relates more particularly to such a multicontact electrical connector wherein one or more RF filter elements comprising either a capacitor or an inductor, or both, are electrically coupled with contact terminals of one of the connector members so as to attenuate or ground out unwanted RF signals which might otherwise pass through the connector.
In many circuits it is necessary or desirable to include and RF filter which may include one or more capacitors, and which preferably also includes at least one inductor, and it is frequently particularly desirable to embody such RF filter components in an electrical connector so that the circuit is not interrupted by the filter at any other point. For example, in vehicle electrical systems the embodying of RF filter components in one or more electrical connectors eliminates the necessity for a large amount of expensive shielding which would otherwise be required.
However, because of the size limitations of electrical connectors, and also because of the requirement that optimum electrical characteristics must be maintained in electrical connectors, it has heretofore presented a very difficult problem to incorporate such RF filter components in an electrical connector. Prior art attempts to produce electrical connectors having one or more RF filter components therein have resulted in connectors which are particularly difficult to assemble and wherein neither the contact terminals nor the RF filter elements or components could be removed and replaced in the event of damaged parts or necessity to change the values of the filter components, or to reconstitute any of the circuits associated with the connector.
In view of these and other problems in the art, it is an object of the present invention to provide an electrical connector member having one or more contact terminals mounted therein, and which embodies one or more RF filter elements or components electrically coupled with each of the contact terminals so as to suppress or ground out unwanted RF signals which may be applied to the terminals.
Another object of the present invention is to provide an electrical connector of the character described wherein one of the connector members embodies one or more RF filter elements or components electrically associated with one or more contact terminals therein, and wherein the contact terminals and the RF filter elements are removable and replaceable in the connector member so that damaged parts can be removed and replaced and the values of the filter elements or components can be changed.
Another object of the invention is to provide an electrical connector member of the character described having one or more contact terminals mounted therein, wherein at least one capacitor component is arranged so as to shunt RF signals from each contact terminal to a conducting shell of the connector so as to ground out RF signals which may be applied to the contact terminals, and which may also include inductor means associated with each contact terminal so as to present a barrier to RF signals which may be applied to the terminals.
A further object of the present invention is to provide an electrical connector member of the character described having RF filter components therein, wherein the RF filter components are mounted on the individual contact terminals, and these contact terminals are removably supported in the body of the connector member, whereby the RF filter components can be replaced merely by removal and replacement of the contact terminals themselves.
It is an additional object of the invention to provide an electrical connector member of the character described having RF filter components, wherein the filter components are primarily mounted in the body of the connector member and are adapted to cooperate with contact terminals which are removably supported in the body of the connector member.
These and other objects and advantages of the invention will become more apparent from a consideration of the description which follows taken in conjunction with the drawings.
In the drawings, FIG. 1 is an axial sectional view, partly in elevation, illustrating a presently preferred embodiment of the invention wherein the RF filter elements or components are mounted on removable contact terminals.
FIG. 2 is a greatly enlarged fragmentary section of a part of FIG. 1, illustrating details of construction of one of the contact terminals and its mounting in the connector member.
FIG. 3 is a schematic diagram illustrating the RF electrical circuit associated with the contact terminal shown in FIG. 2.
FIG. 4 is an enlarged fragmentary section showing a connector member having an external shell similar to that of FIG. 1, but embodying an alternative contact terminal and terminal supporting structure wherein the RF filter components are primarily embodied in the body portion of the connector member.
FIG. 5 is an enlarged fragmentary sectional view illustrating a further embodiment of the invention which is a variation of the embodiment shown in FIG. 4.
Referring at first to FIGS. 1 and 2 of the drawings, a connector member 10 is shown, and comprises the receptacle portion of an electrical connector which also includes a mating plug portion (not shown). The connector member 10 includes a tubular outer metal shell 12 having a rearward portion 14 and a forward skirt portion 16, with an inwardly directed flange 18 between the portions 14 and 16.
A contact terminal supporting body 20 is removably mounted in the rearward portion 14 of shell 12, being retained against forward movement in the shell by abutment of a forwardly facing shoulder 22 on the body 20 against flange 18 in the shell. A rearwardly facing shoulder 24 on the body 20 is engaged by a retainer 26 to prevent rearward movement of body 20 in the shell, the retainer 26 being fastened to the shell by means of screws 28.
The contact terminal supporting body 26 is made in two parts, a rearward body portion 39 composed of a conducting material and a forward body portion 32 composed of insulation material. The body portions 30 and 32 may be bonded together as by means of a suitable bonding cement. Suitable conducting materials of which the rearward body portion 30 may be composed, which are given by way of example only and not of limitation, are solid metal, which may be die cast or machined, sintered metal, or a resin modified by inclusion of a powdered metallic filler so as to be conductive, such as diallyl phthalate embodying finely powdered copper. The advantage of such a resin modified to be conductive is that it can be molded much in the manner of an ordinary connector insulation body.
The contact terminal supporting body has a plurality of terminal receiving bores 34 extending therethrough from the rearward face 36 of the body 20 to the forward face 38 of body 20. Each of the bores 34 has a generally cylindrical forward constricted portion 40 disposed in the forward insulation portion 32 of the body, and an enlarged rearward portion 42, the bore including a rearwardly facing shoulder 44 between the generally cylindrical forward portion 40 and the enlarged rearward portion 42. Additionally, a constriction is provided at the rear end of the enlarged rearward portion 42 of the bore so as to present a forwardly facing shoulder 46.
A contact retention sleeve 48 is seated in the enlarged rearward portion 42 of the bore, the sleeve 48 comprising a split spring sleeve member that can be contracted and inserted into the bore through the rear end thereof and then permitted to expand into position as best shown in FIG. 2 so that its forward edge is abuttable against the rearwardly facing shoulder 44 to prevent forward movement of sleeve 48 and its rearward edge is abuttable against the forwardly facing shoulder 46 to prevent rearward movement of sleeve 48 in the bore. One or more spring retention fingers 50 are struck inwardly from the wall of the contact retention sleeve 48 so as to incline forwardly and radially inwardly. These spring retention fingers 50 preferably are integrally joined with the body of sleeve near the rear end of the sleeve. Additionally, one or more spring contacting fingers 52 are struck inwardly from the wall of the retention sleeve 48 forwardly of the retention fingers 50. Electrical connection is present from the contacting fingers 52 through the sleeve 48 and through the conducting rearward body portion to the outer metal shell 12, so that when the outer shell 12 is grounded, the spring contacting fingers 52 will likewise be at ground potential.
The bores 34 extending through the terminal supporting body 20 are adapted to receive respective socket contact terminals 54. However, it is to be understood that the invention is equally applicable to pin contact terminals, or to any other type of terminal capable of mating with an opposing terminal in another connector member, as for example a hermaphrodite type of terminal. Each of the socket contact terminals 54 includes a generally cylindrical tubular forward socket portion 56 which fits into the forward bore portion and is adapted to receive a mating pin, a reduced cylindrical intermediate portion 58, and a generally cylindrical tubular rearward portion 60 within which a conductor wire may be soldered or crimped.
Mounted on the reduced cylindrical intermediate portion 58 of the contact terminal 54 is an annular RF filter unit 62. This unit includes a generally cylindrical capacitor barrel 64 composed of conducting material and which, like the conducting rearward body portion 30, may be composed of solid or sintered metal or a resin that is modified to be conductive. If the conducting capacitor barrel 64 is of this modified conductive resin type, it can readily be molded in position about the reduced cylindrical portion 58 of the contact terminal. The barrel 64 has a cylindrical inner wall 66 and a cylindrical outer wall 68, and includes a forward surface 70 and a reduced rearward portion 72 presenting a rearwardly facing shoulder 74.
An annular inductor bead 76 is disposed within the barrel 64 of RF filter unit 62 intermediate the ends of the barrel 64, the inductor bead 76 having a cylindrical inner surface 78. The inner surface 78 of head 76 may either be in direct contact with the reduced cylindrical intermediate portion 58 of the contact terminal, or it may be slightly spaced outwardly therefrom. Even if the head 76 is in direct contact with the portion 58 of the terminal, the volume resistivity of the bead is so high that there is no substantial DC. leakage between the terminal 54 and the barrel 64. Inductor bead 76 is composed of a ferromagnetic material having a suitable permeability. Ferrite is the presently preferred material for the inductor bead 76, this being a ceramic ferromagnetic material. It is to be understood, however, that the invention is not limited to the use of any particular type of ferromagnetic material for the inductor bead 76.
A pair of dielectric sleeves $0 and 82 are disposed,
I respectively, rearwardly and forwardly of the inductor bead 76 between the cylindrical intermediate portion 58 of the terminal and the cylindrical inner wall 66 of the barrel 64. Although any suitable dielectric material may be employed in the dielectric sleeves and 82, a presently preferred dielectric material is barium titanate, which has a relatively high dielectric constant. Examples of other materials which can be used are Teflon and nylon. Even an air gap could be employed as the dielectric if desired.
Each end of the capacitor barrel 64 is electrically isolated from the adjacent opposed shoulder on the contact terminal 54 by a layer 83 of insulating material.
The RF filter unit 62 provides an RF circuit arrangement like that illustrated diagrammatically in FIG. 3, which is a 1r type of filter. Thus, the contact terminal 54 is represented in FIG. 3 as a conductor 84. Disposition of the inductor bead 76 about the reduced intermediate portion 58 of the terminal has the electrical effect of the inductor 86 in the conductor 84 in FIG. 3. The gap defined by dielectric sleeve 80 between the reduced intermediate portion 58 of the contact terminal and the barrel 64 has the effect of the capacitor 88 shown in the diagram of FIG. 3, while the similar gap defined by the dielectric sleeve 82 at the other side of the inductor head 76 has the electrical effect of the capacitor 89 shown in the diagram of FIG. 3. Grounding of the capacitors is effected by the electrical connection between the spring cont-acting fingers 52 of the retention sleeve 48 and the cylindrical outer wall 68 of the capacitor barrel 64.
It is to be understood that the capacitance across each of the dielectric sleeves 80 and 82 can be varied by variation of the type of dielectric material used, width of the dielectric gap, length of the dielectric gap, and diameter of the dielectric gap. Similarly, it is to be understood that the amount of inductance of the inductor head 76 may be varied by varying the composition of the ferromagnetic material employed therein, and by varying the size and configuration of the head.
The contact terminal 54 is removably mounted in the bore of the supporting body 20 merely by insertion of the terminal into the bore from the rearward end of the bore. 'For ward travel of the terminal in the bore is limited by abutment of the forward surface 70 of barrel 64 against the rearwardly facing shoulder 44 in the bore. As the contact terminal 54 is being inserted into the bore, the annular enlargement presented by the barrel 64 will deflect the spring retention fingers 5t outwardly until the rearwardly facing shoulder 74 on the barrel 64 passes the free ends of the fingers 50, at which time the fingers 50 will spring back inwardly behind the shoulder 74 on the barrel 64 to releasably lock the contact in its operative position in the bore. In this position, the spring contacting fingers 52 will be resiliently engaged against the outer cylindrical wall 68 of the barrel 64 in electrical contact therewith.
Removal of the contact terminal 54 from the bore is effected by insertion of a suitable tool into the rear end of the bore so as to deflect the retention fingers 50 outwardly past the rearwardly facing shoulder 74 on the barrel 64, permitting manual withdrawal of the contact from the bore.
This removable mounting of the contact terminals 54 in the bore permits replacement of one or more of the terminals for any desired reason, such as in the event of damage to a terminal or to the parts, thereof effecting the electrical characteristics of the RF filter unit, or for changing the values of the capacitor or induct or components of one or more of the RF filter units, or for re constituting one or more circuits associated with the connector.
FIG. 4 illustrates an alternative embodiment of the invent-ion wherein the :RF filter unit is carried principally in the body of the connector member rather than in the contact terminal itself. The connector body, designated generally by the numeral 90 in FIG. 4, may be mounted in an outer metal shell 91 generally similar to the shell 12 shown in FIG. 1. However, the shell 91 is shown as a plug shell rather than a receptacle shell as in FIG. 1.
The body 90 is made up principally of a series of plates which are bonded together as a unit, and including, from rear to front, a rearward insulator plate 92 a first conductive plate 94, an inductor plate 96, a second conductive plate 98, and a forward insulator plate 100. A plurality of parallel terminal receiving bores 102 extend through the body 90 from its rearward face 104 to its forward face 106.
The rearward insulator plate 92 has an enlarged rear- Ward portion 108 of each of the bores 102 therein, each bore presenting a rearwardly facing shoulder 110 at the forward end of the enlarged portion 108. An inwardly directed lip is provided proximate the rear end of each enlarged bore portion 108 presenting a forwardly facing shoulder 11-2. A contact retention sleeve 114 comprising a split spring sleeve is engaged in the enlarged bore portion 108, and is prevented from moving forwardly by the shoulder 110 and from moving rearwardly by the shoulder 112. The contact retention sleeve 114 has one or more spring retention fingers 116 struck inwardly from the wall thereof so as to extend forwardly and radially inwardly from their connections with the body of the sleeve 114.
The contact terminal 118 shown in FIG. 4 is again one of a plurality of socket contact terminals mounted in the respective bores 102, although it is to be understood that a pin contact terminal or any other desired type of terminal may be employed. The contact terminal 118 has an elongated body portion 120 of general- 1y cylindrical external configuration which is disposed primarily in the portion of the bore 102 which extends through the plates 94, 96, 98 and 100, and this elongated Ibody portion 120 has a tubular forward socket portion 122 adapted to receive a mating pin. The contact terminal 118 includes an annular collar 124 immediately to the rear of the elongated body portion 120, and the rearward end of contact terminal 113 comprises a tubular portion 126 within which a wire conductor may be soldered or crimped.
The contact terminal 118 is engaged in the bore 102 by insertion from the rear end thereof, and the forward limit of travel of the terminal 118 is defined by engagement of the annular collar 124 against the rearwardly facing shoulder 110 in the bore. During insertion of the contact terminal 118 into the bore, the annular collar 124 deflects the spring retention fingers 116 radially outward- =ly until the collar 124 is in front of the free ends of the spring fingers 116, at which time the fingers 116 snap radially inwardly behind the collar 124 to releasably lock the terminal in its operative position as shown in FIG. 4. The terminal may then be removed by insertion of a suitable tool into the rear end of the bore so as to deflect the fingers 116 radially outwardly past the outer extremity of the annular collar 124, which permits extraction of the contact terminal from the rear end of the bore.
The conductive plates 94 and 98 may be die cast or machined of metal, or may comprise sintered metal or a resin modified to be conductive, such as the aforesaid diallyl phthalate which includes finely powdered metallic filler, and the outer peripheries of these conductive plates 6 94 and 98 are electrically contacted to the metallic outer shell by means of a suitable annular contacting spring 128.
The inductor plate 96 is composed of a suitable ferromagnetic material having the desired permeability, as for example a ferrite composition. The volume resistivity of inductor plate 96 is so high that there is substantially no D'.C. leakage between the terminal 118 and either of the conductive plates 94 and 98, even if the inductor plate 96 were to touch the terminal.
The portion of the bore 102 lying within the first conductive plate 94 is lined with a dielectric sleeve 130, while the portion of bore 102 within the second conductive plate 98 is lined with a dielectric sleeve 132, the dielectric sleeves 130 and 132 being composed of any suitable dielectric material having the desired dielectric characteristics, as for example barium titanate, Teflon, nylon, or if desired simply an air gap.
The structure shown in FIG. 4 provides a 1r type of RF filter similar to the structure of FIGS. 1 and 2, as diagrammatically illustrated in FIG. 3. Thus, the contact terminal 118 is represented by the conductor 84 in FIG. 3, and the portion of the inductor plate 96 immediately surrounding the contact terminal functions as the inductor 86 of FIG. 3. The gap defined by dielectric sleeve 130 between the contact terminal 118 and the bore portion which extends through the first conductive plate 94 is represented by the capacitor 88 in FIG. 3, while similarly the gap defined by dielectric sleeve 132 between the contact terminal 118 and the bore portion within the second conductive plate 98 is represented by the capacitor 89 in FIG. 3.
The structure shown in FIG. 5 is similar to that of FIG. 4, with the exception that the inductor plate 96 of FIG. 4 has been replaced in FIG. 5 by an insulator plate 134 which supports a plurality of inductor beads 136 in annularly disposed relationship about the respective contact terminals 118, with an inner cylindrical surface 138 of each inductor bead 136 defining a portion of the respective bore 102. By thus employing a separate inductor bead 136 in the insulator plate 134 proximate each of the bores 102, there can be no possible inductive coupling between adjacent contact terminals supported in the body 90. Although a small amount of such inductive coupling might sometimes be present where the unitary inductor plate 96 is employed as in FIG. 4, with all of the bores 102 extending through the single plate 96, normally such inductive coupling will not be sufficient to interfere with satisfactory operation of the connector.
While the instant invention has been shown and described herein in what are conceived to be the most practical and preferred embodiments, it is recognized that departures may be made therefrom within the scope of the invention, which is therefore not to be limited to the details disclosed herein, but is to be accorded the full scope of the claims so as to embrace any and all equivalent devices.
1. An electrical connector and filter assembly comprising a body member having a conductive outer portion and having a bore extending therethrough, a contact terminal slidably mounted in said bore and adapted to be separably connected to a mating terminal in a second body, an electrically conducting capacitor member mounted on said contact terminal in encircling relationship to a portion thereof, electrically insulated therefrom and having a surface spaced from an opposed surface of said terminal to define a capacitor gap therewith, inductor means composed of ferromagnetic material mounted on said terminal in encircling relationship to a portion thereof, electrically conducting spring means supported on one of said members and releasably engaging the other member to releasably lock said terminal in said bore, said spring means conductively engaging said capacitor member and being electrically connected to said conductive outer portion of said body member whereby upon release of said spring means said terminal, capacitor member and inductor means may be removed as a filter unit from said body.
2.'An electrical connector and filter assembly as defined in claim 1 wherein said spring means is mounted on said body member in said bore to provide a ground connection and releasably engages a shoulder on said capacitor member.
3. An electrical connector and filter assembly as defined in claim 1 wherein said capacitor member is provided with a second surface, axially spaced from said firstnamed surface and opposed to a surface of said terminal to define a second capacitor gap therebetween, said inductor means being disposed between said two capacitor gaps so as to define a pi filter.
4. An electrical connector and filter assembly as defined in claim 2 wherein said capacitor member comprises a unitary sleeve, said inductor means comprising an annular ring seated in the inner periphery of said sleeve.
5. An electrical connector and filter assembly as defined in claim 1 wherein the space between said opposed surfaces is occupied by a solid dielectric material of high dielectric constant and low loss, such as BaTiO and said ferromagnetic material is ferrite.
6. An electric connector and filter assembly as defined in claim 1 including a dielectric sleeve between said opposed surfaces to provide capacitance reactance.
References Cited by the Examiner UNITED STATES PATENTS 2,383,890 8/45 Robinson 33379 2,403,252 7/46 Wheeler 333--33 2,548,881 4/51 Ferrill 33381 2,549,424 4/51 Carlson 333-79 2,569,667 10/51 Harvey et al 333-79 2,667,622 1/54 Weber et a1 33381 2,779,002 1/57 Foster et al 33381 3,002,166 9/61 Weinschel 33381 3,005,967 10/61 Weinschel 3338l HERMAN KARL SAALBACH, Primary Examiner.