AU608356B2 - Electrical plug - Google Patents

Description

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r~j~w COMMONWEALTH OF AUS. tALIA PATENTS ACT 1952 COMPLETE SPECIFICATION

(ORIGINAL)

Form FOR OFFICE USE Short Title: Int. Cl: Application Number: Lodged: This document contains tlhe amendments made under Section 49 and is correct for printing.

PI 4002 27th August 1987 '9, 09 9 9 9 O O 9 9 1 *I *0 99 9I 9 Complete Specification-Lodged: Accepted: Lapsed: Published: Priority: Related Art: TO BE COMPLETED BY APPLICANT Name of Applicant: Address of Applicant: Actual Inventor: Address for Service: ACCESS COMMUNICATIONS PTY. LIMITED 33 Alleyne Street, Chatswood, N.S.W. 2067, Australia .j GRIFFITH HACK CO.

71 YORK STREET SYDNEY NSW 2000

AUSTRALIA

Complete Specification for the invention entitled: "ELECTRICAL PLUG" The following statement is a full description of this invention, including the best method of performing it known to me/us:- 8911A/elm ALi This invention relates to an electrical connector or plug and has particular application for use in connecting telephones to Telecom Australia's standard telephone outlets The shape of the plugs are dictated by the shape of the sockets to which the plugs are connected or connectable and by Telecom's requirements.

The prior art plug has a main housing and a cover fitted to the housing by way of a screw being engaged with a nut held captive in the housing. From one side of the housing there extends three pins plus a locating spigot. A hole is provided in the housing opposite the side from which the pins extend to allow access for an electrical cable to be fitted to the plug. Each pin comprises two electrically conductive contact strips extending along a divider, one contact strip extending along one side of the divider and the other extending along an opposite side of the divider, the dividers being generally elongate and flat. The pins are formed as separate items to the housing and are press fitted into locating holes formed in the housing and located therein by means of a protruberance formed in each hole which locates into a notch formed in each divider. The holes are formed as slots in the housing which are closed by the cover thereby holding the pins within the holes.

S. The electrical contact strips are stamped from a sheet of electrically conductive metallic substance and are arranged to mate with similar strips in the socket to which 0 the plug is to be connected. The inner or rear ends of the strips are electrically connected to wires contained in the cable fitted to the plug. The electrical contact strips are located in recesses formed along the side of the dividers to retain the strips therealong. The strips are formed so that Sa the outer end, which is in contact with the divider, is slightly curved to provide a smooth lead in for the strip I into the socket and to provide a slight biasing allowing the 1, 5 strips to be resiliently deformed so that the strips of the plug can be held in tight contact with the contact strip in the socket. The inner ends of the strips are also bent or -2 shaped so that each inner end is spaced from the divider to allow connection of the wires to the strips. The dividers themselves are reduced in thickness in the area adjacent the inner end of the strips to provide greater access to the strips for connecting the wires thereto and extend past the end of the strips to provide an electrical shield or insulation to prevent shorting between the contact strips of the same pin. The strips are also stepped half way along to avoid the notch in the divider for the locating protruberance in the locating hole.

The contact strips are generally made from 0.45mm thick Monel Alloy 400 to Telecom Australia's specification 1223 and the housing, dividers and cover are made from polypropelene, also according to Telecom Australia's specification 1223. The Monel Alloy 400 is a very expensive material and represents a significant portion of the cost of manufacturing of the plug. The strips are pressed from a strip of the material as wide as the strip are long, and because of the step in the contact strip up to 30% of the alloy is lost due to wastage, as can be more clearly seen from Figures 9, 10 and 11 which depicts a row of contact 0 00 o strips as they are punched from a sheet of material.

Also, because of the step portion, there are formed o left and right hand electrical contact strips as the strips are not reversible. Therefore the complete plug requires a cover, a housing, 3 dividers, 3 right-hand contact strips and 3 left-hand contact strips, therefore requiring the contact strips to be sorted into two catagories which may lead to confusion or time wasted when these two catagories 30 are intermixed.

64 A Therefore, the cost of manufacturing a telephone plug 4 At can be reduced if less alloy material is wasted during the stamping of the contact strips. The cost of assembling the Atli' plug may be furlther reduced if the contact strips are made t-41 5 identical rather than having two separate catagories.

The present invention therefore provides an electrical t Splug frojectingr a telephone having a housing with a locating spigotm projecting therefrom, -3a cover for the housing, a plurality of elongate pins each comprising a divider and two identical, electrically conductive contact strips on opposite sides of the divider, the pins passing through respective slots formed in a wall of the housing and extending substantially parallel to and in the same direction as the locating spigot; wherein each pin is held captive in its slot by the cover, by a locating protruberance formed in the slot and which co-operates with a notch in the divider, and by an enlargement of the width of the divider which co-operates with matching walls of the slot.

Notwithstanding any other forms that may fall within its scope, one preferred form of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 illustrates a telephone plug in accordance with the present invention; Figure 2 depicts a part-sectional view through the plug of Figure 1 showing how the electrical contact strips extend along the dividers; 0 Figure 3 depicts a cross-sectional view through the 94 plug of Figure 1 along line A-A.

99.4 Figures 4 and 5 depict a divider used in a plug in accordance with the present invention.

844449 Figures 6 and 7 illustrate an electrical contact strip used in a plug according to the present invention; Figure 8 illustrates a plurality of electrical contact strips as shown in Figures 6 and 7 as arranged to be punched 30 out of a sheet of material; lri Figures 9 and 10 depict a prior art electrical contact strip; and Figure 11 depicts a plurality of prior art electrical ftb contact strips of the type as shown in Figures 9 and 10, as arranged to be punched out of a sheet of material; Figures 1, 2 and 3 illustrate a electrical plug commonly used with telephone systems. The plug comprises a Is) i i 4 2 housing 10 having a locating spigot 11 projecting from one side of the plug. Projecting parallel to and in the same direction as the locating spigot are three pins, which each comprise a divider 12 and two contact strips 15, the pins are held captive in slots 14 in the housing by a cover 13.

As can be more clearly seen in Figure 2, along two sides of each divider extend respective, electrically conductive, contact strips 15. The dividers, as more clearly shown in Figures 4 and 5, are substantially planar and elongate having a notch 16 formed in the lower edge thereof. A recess 17 is formed along opposite sides of each divider and arranged to receive the contact strip 15. The dividers have an enlarged portion 26 located in the vicinity of the notch. This enlarged portion is in the form of a shoulder extending on either side of the divider with tapered forward facing surfaces 27. The tapered surfaces 27 and the outer ends of the shoulder support the respective contact strips where they are bent or otherwise provided with an offset 28 to provide clearance from the divider to allow connection to an electrical wire. The notch portion 16 is used to locate the divider in the slots of the housing and the pins o are retained in the slots 14 by the cover which closes the S slots securing the pins therein. Each slot 14 has a protruberance 18 which co-operates with the notch 16 to 4425 locate the dividers in the slots. During normal use, the 4 So cover would only be removed when a cable is being connected to the contact strips.

The cable enters the housing via access hole 19 which is also closed by the cover. The wires from the cable are then connected to the electrical contact strips in the usual manner. The cover is secured to the housing by means of a screw 20 and a nut 21 held captive in the housing. The housing has a number of ribs 22 along two sides of the housing acting as finger ips when inserting or removing the plug from a socket, not shown.

The use of contact strips having substantially straight parallel edges in plan view allows the strips to be punched 5332/ M r from a sheet of material with minimum wastage of the material. As the sheet of material 25 from which the contact strips are made represents a significant part of the costs of the manufacturing of the plug, any saving of this material results in a lowering of the cost of manufacturing the plug. The use of the straight sided electrical contact strips represents a saving of up to 30% in the cost of the material from which the contact strips are made over the prior art contact strip which has stepped sides resulting in excess material 31 being wasted between adjacent contact strips when being pressed from the sheet. This can be more clearly seen from Figures 9, 10 and 11.

The dividers of the preferred embodiment as shown in Figure 3 are modified from the shape of the prior art dividers to allow the notches to be slightly smaller and the protruberances in the slots in the housing are similarly reduced in size so that the necessity for the stepped portion in the electrical contact strip is no longer required, but the notches and the protruberance are still sufficient to maintain the divider in captive location with respect to the housing. The shape of the divider and the housing co-operate to hold the divider in the desired location. The electrical contact strips are also held in position along the dividers by the housing. One end of the contact strip is offset from the other end of the strip to Sallow electrical connection of the strip to the electrical wire of the cable fitted to the plug. The other end of the strip is slightly curved and the recess in the divider is similarly shaped to provide a smooth or non-abrupt join between the contact strip and the divider when the combined t 4 divider and electrical strips are viewed from the outside allowing the dividers and strips to be easily inserted into the socket.

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Claims (3)

1. 2. An electrical plug as defined in claim 1 wherein each contact strip has two substantially straight longitudinal edges running from end to end and subsisting in first and second spaced parallel planes, is located in a ,0 ~recess in a third plane formed along the respective side of the divider and is sandwiched between the enlargement of the divider and the matching walls.
2. 3. An electrical plug as defined in any preceding claim wherein the dividers have a constant or reduced width, with respect to the enlargement, in the interior of the plug to allow clearance between the contact strips and their associated divider for connection of electrical wires.
3. 4. An electrical plug as defined in Claim 3 wherein the enlargement of the dividers is in the form of a shoulder extending from an opposite sides of the divider and having tapered forward facing surfaces. An electrical plug for a telephone substantially as hereinbefore described with reference to Figures 1 to 8 of the accompanying drawings. DATED this 10th day of October 1990 ACCESS COMMUNICATIONS rO'1 K LBy their Patent Attorneys GRIFFITH HACK CO. J,-7-