Electrical Connector Having Rf Filter

Abstract

An electrical connector assembly having a plurality of permanently mounted filter contacts therein for eliminating undesired high frequency currents and a second plurality of removable electrical contacts mateable with a respective filter contact. This combination provides an air-tight filter connector assembly having removable contacts so that incoming wires may be soldered or crimped thereto, thereby avoiding any damage to the filter contact during the connection of the incoming wires to the connector.

Description

BACKGROUND OF THE INVENTION

This invention relates to electrical connectors of the type having contacts that have capacitive and inductive components arranged thereon to filter out predetermined frequencies. This invention is more particularly related to an improved filter connector assembly that includes a removably mounted filterless contact which may be removed from the connector assembly so that a wire may be soldered or crimped to one end of the contact while the contact is separated from the connector assembly.

In television and other electronic circuits utilizing high frequencies, portions of the circuits radiate electrical energy and thereby induce undesired high frequency currents in circuit leads intended for carrying low frequency and direct current signals. A common method for disposing of the undesired signals is to channel the leads through a shielding wall. Encircling and intermediate leads and shields are low reactant filters electrically connected between the leads and the shields. The filters serve as high impedance paths to the low frequencies and direct current signals and low impedance paths to the high frequency signals. Thus, the desired signals pass along the lead so the external circuitry and the undesired signals are bypassed through the shields.

Examples of electrical connectors of the type having one or more RF filter assemblies that generally include a capacitor and inductor element may be found in the following patents that relate to filter connector assemblies and the filter contacts themselves: U.S. Pat. No. 3,435,387 entitled "Solderless Mounting Filter Connections," issued to J. F. Reinke et al, Mar. 25, 1969, which describes a feedthrough connector assembly; U.S. Pat. No. 3,588,758 entitled "Electrical Connector Filter Having Dielectric and Ferromagnetic Tubes Bonded Together with Conductive Electrode Layers and Having Nonintegral Connecting Spring," issued to D. J. Hurst, June 28, 1971 which relates to an electrical connector contact filter assembly; and U.S. Pat. No. 3,462,715 entitled "Removable Electrical Connector Filter Assembly," issued to F. W. Schor, Aug. 19, 1969, which describes the components and assembly of an electrical connector contact and its associated filter circuit. The aforementioned patents are expressly incorporated into this specification by reference.

One ever present problem with multiconductor filter connectors, exemplified by U.S. Pat. No. 3,435,387, is that to allow crimping of incoming wires to the filter contacts, the filter contacts had to be removable because there was insufficient space within the connector housing to allow personnel to crimp a wire to the wire receiving end of the filter contact. Further, in filter connector assemblies wherein the filter contacts were permanently mounted, specialized personnel and equipment were required for the soldering process to attach the incoming wires to the contacts. The specialized personnel and equipment being necessary because of the soldering technique necessary to avoid injury to the filter assembly which is heat sensitive, and, in fact, can be rendered ineffective by the application of too much heat to the contact assembly by unskilled personnel.

SUMMARY OF THE INVENTION

This invention provides an RF filter connector that may be assembled in the field without the requirement of a specialized technician for connecting the incoming wires to the RF filter connector.

The invention is an RF filter connector assembly characterized by an electrical connector shell (40) having permanently mounted therein a filter contact assembly (5) having a mating portion (1,3) at each end and a removably mounted contact (50) having one end (51) adapted to mate with one end (3) of the filter contact (5) and an opposite end (52) for receiving an incoming wire (60).

In one embodiment of the invention, the RF electrical filter connector comprises: a housing (40), a filter element formed of an outer ceramic tubular member (20) and an inner ferromagnetic tubular member (10), the outer ceramic tubular member having at least a portion of its outer surface (21) conductively coated and a portion of its inner surface (22) conductively coated, the inner (22) and outer (21) surface coating electrically isolated from each other; a first electrical contact having a mating end (1) and a second opposite mating end (3); means (30,31) for mounting the filter element around a portion of the contact, the mounting means (30,31) being electrically conductive to electrically connect together the conductive coating (22) on the inside of said ceramic tubular member (20) and said contact; and means (42) for mounting the filter contact assembly (5) within said housing (40) so that the first mating end (1) is accessible from one end of said connector housing (40); a second electrical contact (50) removably mounted (49,53) within said connector housing (40), said second contact (50) having at one end a wire receiving portion (52) and at the opposite end a portion (51) mated with said second end portion (3) of said first contact.

Accordingly, it is an object of this invention to provide a filter connector with a removable and filterless contact that is mateable with a filter contact assembly that has previously been permanently mounted within the connector by soldering.

It is another object of this invention to provide a filter connector that maintains acceptable filtering characteristics after crimping or soldering incoming wires to the connector contacts.

It is another object of this invention to provide a filter connector that does not require personnel having special technical skills to solder the incoming wires to the connector contacts.

It is also another object of this invention to provide a filter connector that has removable contacts for installation of incoming wires and at the same time provides an air-tight barrier between the incoming wires and the mating end of the connector.

It is still a further object of this invention to provide a filter connector that consistently provides good electrical continuity between the filter assembly and the connector shell to assure optimum attenuation of the undesirable signals.

The above and other objects and features of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings and claims which form a part of this specification. The use of numerals is intended for the purposes of clarification only. They are not intended to limit the invention to the specific embodiment referenced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a filter connector incorporating the principles of this invention.

FIG. 2 is an axial cross-sectional view of the filter contact assembly shown in FIG. 1.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring now to the drawings, FIG. 1 illustrates an RF filter connector. The filter connector comprises: a metal shell (40); a filter contact assembly (5); means for permanently mounting the filter contact assembly (5); a second contact (50) mateable with the filter contact; and means for releasably mounting the contact (50) within the housing (40).

The means for permanently mounting the filter contact assembly (5) comprises an electrically conducting ground plane or member (42) having an aperture therein for receiving the filter contact assembly (5), the ground plane (42) being soldered (70) to an outer conductive coating on the filter contact assembly (5); an epoxy of thermosetting compound (45) for sealing the filter contact (5) in air-tight relationship to the connector shell (40); a rigid dielectric insert (46) for maintaining the filter contact assembly (5) in a fixed position within the connector shell (40); and a resilient insert (47).

The means for releasably or demountably mounting the second contact (50) includes: a rigid dielectric insert (48) having an axial bore therein that contains a contact retention assembly (9) having one or more inwardly and radially extending deflectable fingers (49) that engage the rearward facing shoulder (53) of contact (50) when the contact (50) is mounted in the axial bore to prevent rearward movement of the electrical contact (50) until said deflectable fingers (49) are deflected outwardly and away from the rearwardly facing shoulder (53). Examples of similar retention mechanisms may be found in U.S. Pat. No. 3,200,355 entitled "Electrical Connector Having RF Filter," issued to T. E. Dahlen, Aug. 10, 1965.

A resilient grommet (43) having an axial bore therethrough forms a moisture seal around wire (60) when contact (50) is inserted in mated relationship with the filter contact assembly. A sealant (44) such as a fluid silicon that solidifies at ambient temperatures is used to seal the grommet (43) in the connector housing (40).

The removable contact (50) includes a mating end (51), such as a standard socket contact portion, an enlarged middle portion having a rearward facing shoulder (53) and a wire receiving opposite end portion (52) in the form of a well for receiving the bared end of a conductor (60) which is crimped to provide a mechanical and electrical linkage between the wire (60) and the removable contact (50).

FIG. 2 illustrates the filter contact (5) which is permanently mounted within the connector assembly. The filter contact (5) includes an electrical contact having mateable portions (1,3) at opposite ends thereof. In this embodiment the electrical contact has at one end (1) a pin type contact and at the opposite end (3) another pin type contact for mating with the socket of the removable contact (50) shown in FIG. 1. The electrical contact may include an enlarged portion (2) whose function is to locate the inductive and capacitive portions of the filter element on the electrical contact. The filter elements of the assembly for attenuating signals of predetermined frequencies includes an inner ferromagnetic tubular member (10) which functions as the inductive element of the filter assembly and an outer ceramic tubular member (20) which functions as the capacitive element of the filter assembly. The ceramic tubular member (20) has at least a portion of its outer surface (21) conductively coated and a portion of its inner surface (22) conductively coated with the inner (22) and outer (21) surface being electrically isolated from each other to form the capacitive element. The ceramic and ferromagnetic tubular members are generally secured to the electrical contact by some suitable means such as mounting plates (30,31) which also are electrically conductive so as to electrically connect the inner coating (22) of the ceramic tubular member (20) to the electrical contact. The outer electrical coating (21) is generally connected to ground by the soldering to the ground plane (42) shown in FIG. 1 which is electrically connected to the shell (40) which is generally connected to ground. The filter contact assembly, of course, may be arranged in any manner so long as it performs its filtering function. An alternate arrangement of the filter contact assembly (5) may be found in the previously referenced U.S. Pat. No. 3,435,387 wherein the arrangement of the ceramic tubular member and the ferromagnetic tubular member are reversed.

CONNECTOR ASSEMBLY PROCEDURE

Referring again to FIG. 1, the RF filter connector is assembled as follows: First, the conductive ground plane (42) is placed into the connector housing (40). The electrical filter contact (5) is then inserted in an aperture in the ground plane (42). The connector shell (40), the ground plane (42) and the filter contact (5) are then secured to each other by soldering (70). This particular step is performed by skilled technicians who solder the elements together without injury to the filter element, thereby assuring proper operation of the filter contact (5) within the connector housing (40). Once the filter contact (5) is in place, the cavities on both sides of the ground plane (42) are filled with an epoxy compound so that the passage in the connector housing (40) is air tight. Following this step insert assemblies consisting of rigid dielectric members (46) and resilient interface members (47) are assembled in place. Once the rigid dielectric members and resilient interface members are in place the epoxy portion (45) is heat cured with the connector assembly oriented in such a fashion as to allow the epoxy (45) to fully cover the surface of the rigid dielectric members (46). After completion of the sealing operation, the retention insert assembly for removably retaining the second nonfilter-type contact (50) is inserted into the rear cavity of the connector housing (40). The retention insert assembly consists of a rigid dielectric member (48), a retention mechanism (9), and a resilient grommet (43) which functions to form a moisture seal around the wire (60) when the contact (50) is in mated relationship with the filter contact (5). The rigid dielectric member (48) is permanently secured inside the housing (40) by a staking operation which deforms the housing (40) inwardly at point (41) so that the inner wall of the housing (40) retains the rigid dielectric member (48). The cavity remaining between the inner wall of the housing (40) and the outer wall of the rigid dielectric member (48) and the resilient grommet (43) is filled with a fluid silicon sealant (44) which is cured by exposure to room temperature. This seals the dielectric member (48) and resilient member (49) inside the connector housing (40).

Incoming wires may be attached to the removable contact (50) by either soldering or crimping. In the embodiment shown, an incoming wire (60) has been stripped and the stripped portion inserted into the wire receiving end (52) of the contact (50) and crimped to form a mechanical and electrical bond between the incoming wire (60) and the removable contact (50). The contact (50) may then be inserted into the axial bores in the dielectric member (48) and the grommet (43) until the inwardly facing spring fingers (49) engage the rearwardly facing shoulder (53) of the contact to prevent rearward removal of the contact (50). In the mounted position, the forward portion (51) of the contact (50) is in mated relationship with the pin contact (3) of the filter contact (5). To remove the contact (50) a suitable tool is forced into the axial bores in the dielectric member (49) and resilient member (43) until it reaches the rearwardly facing shoulder (53) of the contact (50). In this position, the tool deflects outwardly the retaining finger (49) allowing the contact (50) to be removed by applying an axial force to the wire (60) in a rearward direction. It can be seen that this arrangement allows unskilled operators to secure the wire (60) to the contact (50) and then insert the contact (50) in its proper position within the connector housing (40).

While a preferred embodiment of the invention has been disclosed, it will become apparent to those skilled in the art that changes may be made to the invention as set forth in the appended claims and, in some instances, certain features of the invention may be used to advantage without corresponding use of other features. For example, although one filter contact assembly is shown, it is understood that the invention applies to an RF filter connector having a plurality (1 to 150) of filter contact assemblies and associated removable contacts. Accordingly, it is intended that the illustrative and descriptive materials herein be used to illustrate the principles of the invention and not to limit the scope thereof.

Claims

Having described the invention, what is claimed is:

1. An electrical connector comprising:

a tubular housing;

a first elongated electrical conductor having an electrical contact portion at each end thereof and having mounted integral thereon means for attenuating electrical signals of predetermined frequencies;

means for fixedly mounting said first electrical conductor within said tubular housing so that one end of said first electrical conductor is accessible for contact from one end of said housing;

a second elongated electrical conductor having a wire receiving end accessible from the other end of said housing and an opposite end in contact with the other end of said first electrical conductor; and

means for releasably mounting said second electrical connector within said tubular housing including:

a first electrically nonconducting member mounted within said tubular housing, said first member comprised of a resiliently deformable material and having a passage therethrough the inner wall of which is in pressure contact with a wire attached to said second electrical conductor;

a second electrically nonconducting member mounted within said tubular housing and adjacent said first member, said second member having a passage therethrough aligned with the passage of said first member and comprised of a rigid nonconducting material; and

means for releasably retaining said second electrical contact, said means disposed in said passage in said second member; whereby said second electrical conductor may be released from said tubular housing so that a wire may be soldered or crimped to said wire receiving end of said contact while said second electrical conductor is separated from contact with said first electrical conductor.

2. An electrical connector as recited in claim 1 wherein said means for fixedly mounting said first electrical conductor includes:

a conducting member comprised of an electrically conducting material and having a passage through which said first electrical conductor is disposed, said conducting member having one portion soldered to said first electrical conductor and another portion soldered to said tubular housing so that said first electrical conductor is immovably mounted within said tubular housing and electrically connected to said housing.