Electrical terminal

Abstract: The application describes an electrical terminal comprising a pair of longitudinally disposed contact members, each having a pair of IDC connectors, one at either end thereof, thereby to link two wire pairs, wherein each contact member comprises a contact arm each extending in a defined direction, the contact arms leading to a pair of arrestor contacts spaced so as to accept a surge arrestor. The defined direction is preferably substantially transverse to the contact members. This enables the surge arrestor to be placed to one side of the electrical terminal, avoiding interference with ingoing and outgoing wires and avoiding inhibiting access to test points. The contact members are preferably parallel within the electrical terminal. The arrestor contacts are preferably spring contacts, thereby to enable replacement of the arrestor. The contact arms more preferably end at the spring contacts. In a particularly preferred embodiment, the contact arms are non-contiguous with the contact members but are joined thereto. This join can be by way of a lug extending from the edge of one of the two members and engaging within a slot of the other. This provides a particularly simple but effective electrical contact. The lug is preferably on the contact members, thereby placing the slot on the contact arms. This also avoids the need to bend a single-piece blank, thereby risking damage to or distribution of the IDC connector. The terminal will ideally be enclosed within a plastics housing, and this will preferably comprise a recess for receiving the surge arrestor, the arrestor contacts extending into the recess. The above electrical terminals can be arranged in a linear array, in which case there is preferably an earth strip associated with the linear array from which extend a plurality of earth contacts into the recesses of the plastics housings.

Description: The present invention relates to an electrical terminal according to the preambles of claims 1 or 11. In the telecommunications field, it is necessary to create a large number of semi-permanent electrical connections between wire pairs. Such connections are usually made with releasable connectors such as shown in our earlier British Patent Applications numbers GB-A-2293699 and GB-A-2303500. The former shows the arrangement in which such connectors, sold by us under the Trade Mark "Mini Rocker" are arranged, i.e. in parallel strips of ten connectors. It is necessary to arrange the connectors in a compact array such that the entire apparatus does not occupy an excessive volume, in view of the large number of wire pairs to be connected. Telephone lines are often suspended above ground where they are susceptible to lightning strike. Lines are also at risk of contact with electrical power cables, whether above or below ground. This means that it is often necessary to provide surge protection for telecommunications contacts. Heretofore, our Mini Rocker connectors have been fitted with surge protection as and where necessary by providing a plug-in module above the Mini Rocker array which contains individual surge arrestors and contacts adapted to extend into test access points and make contact with the internal IDC connectors of the terminal. The present invention seeks to provide a more permanent arrangement of the surge arrestors which does not inhibit access to the test points. Difficulties arise in doing so in that the closely spaced nature of the electrical terminals inhibits the physical room available for the arrestor. Furthermore, a large number of wire pairs needs to be accommodated between the terminals, further inhibiting the dimensional requirements of the terminal. EP-A-0 708 497 discloses a cross connect system for telecommunications use in which a removable plug includes conductors having insulation displacement contacts at one end and tuning fork connectors at the other, with contacts for an arrestor within the plug. The present invention therefore provides an electrical terminal as set out in claim 1. Preferably, the defined direction of the contact arms is substantially transverse to the contact members. This enables the surge arrestor to be placed to one side of the electrical terminal, avoiding interference with ingoing and outgoing wires and avoiding inhibiting access to test points. The contact members are preferably parallel within the electrical terminal. The arrestor contacts are preferably spring contacts, thereby to enable replacement of the arrestor. The contact arms more preferably end at the spring contacts. The join between the contact members and the contact arms can be by way of a lug extending from the edge of one of the two members and engaging within a slot of the other. This provides a particularly simple but effective electrical contact. The lug is preferably on the contact members, thereby placing the slot on the contact arms. This also avoids the need to bend a single-piece blank, thereby risking damage to or distribution of the IDC connector. The terminal will ideally be enclosed within a plastics housing, and this will preferably comprise a recess for receiving the surge arrestor, the arrestor contacts extending into the recess. The above electrical terminals can be arranged in a linear array, in which case there is preferably an earth strip associated with the linear array from which extend a plurality of earth contacts into the recesses of the plastics housings. In another aspect of the present invention, it provides an electrical terminal as set out in claim 11. Embodiments of the present invention will now be described by way of example, with reference to the accompanying figures, in which; Figure 1 is a perspective view of an array of ten connectors according to the present invention; Figure 2 is a view according to Figure 1, with the plastics elements removed thereby showing the electrical contacts and surge arrestor only; and Figure 3 is an enlarged view of the contacts and surge arrestor of the single terminal. Referring to Figure 1, this shows a metallic base unit 10 which comprises a floor portion 12 with upstanding parallel walls 14, 16 at either end thereof. Castellations such as shown at 18 extend upwardly from the upper edge of the walls 14, 16. The castellations 18 on the walls 14 and 16 are arranged so as to be in aligned pairs, one on each wall 14, 16. This permits a ten-connector array of terminals to be fitted onto each pair of castellations. Thus, a plurality of such arrays can be arranged in a generally parallel state to form a two dimensional array. A single such array 20 of ten terminals 22 is shown in Figure 1. This array 20 is held in place by clips 24 which fit over the castellations 18. Each terminal 22 comprises a head portion 26 which is attached to a body portion 28 via a hinge line 30 at the rear of the terminal 22. Thus, the head portion 26 can move in a generally vertical direction. A pair of holes (not visible in Figure 1) are formed on the front face of the head portion 26 and allow access to generally horizontal passageways, suitably sized to accept incoming wires. At the rear of each connector 22 is a socket 32 suitably sized to receive an arrestor 34. The socket 32 is integrally formed with the remainder of the plastics body of the terminal 22, and has an open rear face to allow insertion and removal of the arrestor 34. The open rear face also permits visual confirmation of the presence or absence of an arrestor. An earth bar 36 runs along the rear of the array 20 of connectors 22. A pair of spring contacts 38 at either end of the bar 36 provides grounding to the earthed base 10. A plurality of earth contacts 40 extend from the earth bar 36 and into the socket 32 via the open rear face. These earth contacts 40 are positioned so as to make contact with the earth connection 42 of the arrestor 34. Figure 2 shows the earthing bar 36 and arrestor 34 of Figure 1 more clearly. Figure 2 also shows the IDC connectors 44, 46 within the terminal 22. These each comprise a vertically disposed contact member with an IDC tip such as shown at 48 at either end thereof. The head portion 26 moves, as mentioned before, between a lower position in which the IDC tip 48 projects into the wire-receiving passage and arrays positioned in which the wire receiving passage is clear of the IDC tip 48. Thus, a wire pair can be inserted into the two openings at the front of the connector 22 with the head portion 26 in the raised position. The head portion 26 can then be depressed in a lower position in order to make electrical contact between the wires and the IDC connectors 44, 46. Similar IDC tips exist at the lower end of the contacts 44, 46. These allow connection with an exchange wire, and are supplied in connected form. A movable head arrangement generally similar to the head portion 26 is provided to facilitate connection (as shown in our Application No. GB 2293699). Figure 2 shows the contact arms 50, 52 extending from the two contact members 44, 46 alongside the respective inner walls of the body portion 28 (not shown in Figure 2). These project into the socket 32 and make contact with the contact caps 54,56 of the surge arrestor 34 via spring contacts such as shown at 58. Figure 3 shows the relevant parts of Figure 2 in more detail. It can be seen that the contact member 44 has a small lug 60 extending generally outwardly at roughly its waist portion. Similarly, the contact arm 50 has a pair of downwardly depending lugs 62, 64 which define a gap therebetween into which the lug 60 is an interference fit. This provides an adequate electrical connection whilst allowing ease and reliability of manufacture. Were the contact arms 50 to be formed by bending a one piece blank such that the contact arm 50 extended transversely through the remainder of the IDC connector, this would result in a significant risk of deformation of the remainder of the IDC connector. This in turn would risk degrading the electrical contact between the exchange and consumer wires. Meanwhile, the positioning of the arrestor 34 permitted by this arrangement maintains it clear of both other connectors 32 and the usual access routes for wires to and from the terminals 22. It will be appreciated by those skilled in the art that the above described embodiment is by way of example only, and that many variations can be made thereto without departing from the scope of the present invention.

Claims: An electrical terminal comprising a pair of longitudinally disposed contact members (44,46), wherein each contact member (44, 46) comprises a contact arm (50, 52) extending in a defined direction, the contact arms (50,52) leading to a pair of arrestor contacts (58) spaced so as to accept a surge arrestor (34), characterised in that the contact arms (50,52) are non-unitary with the contact members (44,46) but joined thereto, each contact member having an insulation displacement connector at either end thereof, thereby to link two wire pairs. An electrical terminal according to claim 1 wherein the defined direction is substantially transverse to the contact members (44,46). An electrical terminal according to claim 1 or claim 2 wherein the contact members (44,46) are parallel within the electrical terminal. An electrical terminal according to any preceding claim wherein the arrestor contacts (58) are spring contacts. An electrical terminal according to claim 4 wherein the contact arms (50,52) end at the spring contacts (58). An electrical terminal according to claim 1 wherein the join between the contact arms (50,52) and contact members (44,46) is by way of a lug (60) extending from the edge of one of the two contact members (44,46) and engaging within a slot (62,64) of one of the contact arms (50, 52). An electrical terminal according to any preceding claim wherein the terminal is enclosed within a plastics housing. An electrical terminal according to claim 7 wherein the housing comprises a recess (32) for receiving the surge arrestor (34), the arrestor contacts (58) extending into the recess (32). A linear array of electrical terminals according to any preceding claim. An array according to claim 9 as dependent on claim 8, including an earth strip (36) from which extends a plurality of earth contacts (40) into the recesses of the plastics housings. An electrical terminal comprising a pair of longitudinally disposed contact members (44,46), wherein each contact member (44,46) comprises a contact arm (50,52) extending in a defined direction substantially transverse to the contact member (44,46) and leading to one of a pair of spaced arrestor contacts (58) characterised in that the contact arms (50,52) are non-unitary with the contact members (44,46) but joined thereto, each contact member having a pair of insulation displacement connectors, one at either end thereof, thereby to link two wire pairs.

Inventors: ESCANE RICHARD, ESCANE, RICHARD
Applicants: CHANNELL LTD, CHANNELL LIMITED
Application year: 1998
Main classification: H01R4
IPC codes: H01R4, H01R9