GB2254968A

GB2254968A - Electrical connectors and terminal elements for use therein

Info

Publication number: GB2254968A
Application number: GB9107802A
Authority: GB
Inventors: Alan John Dennis
Original assignee: Pressac Ltd
Current assignee: Pressac Ltd
Priority date: 1991-04-12
Filing date: 1991-04-12
Publication date: 1992-10-21
Anticipated expiration: 2011-04-12
Also published as: GB2254968B; WO1992019022A1; GB9107802D0; AU1457292A

Abstract

An electrical connector comprises a moulding (59) defining housings (60) in which terminal elements (10) are retained. Each element (10) comprises a spine (12) with a longitudinal slot (18) for receiving wire (26) and displacing insulation (28) to provide a connection with the wire core (30), jaws (32) projecting from the spine (12) inclined inwardly forming a second slot (34) parallel with but spaced from the spine (12), the jaws (32) contacting but not cutting insulation (28) and taking strain on external forces applied to the wire (26), a neck (40) of reduced cross-section extending from an end portion of the spine (12), and locking means (39) connected to the spine (12) by the neck (40) and comprising projections (14, 15) projecting transverse to the axis, the neck (40) being capable of permanent deformation so that the locking means (39) can be rotated about an axis A coaxial or parallel with the longitudinal axis to permanently change angular orientation of the projections (14, 15) relative to the spine (12). The means (39) can be inserted through an appropriately shaped opening (66) in moulding (59) with the body of the terminal restrained in housing (60), and rotated to secure the terminal in the housing.

Description

ELECTRICAL CONNECTORS AND TERMINAL ELEMENTS FOR USE THEREIN The invention relates to electrical connectors and especially to so-called insulation displacement connectors of the sort for use with printed circuit boards (PCB). Such connectors commonly comprise conducting terminal elements which are mounted in an insulating housing and provide a means of directly connecting insulating wires to a printed circuit board.

Patent Specification GB 1596347 discloses a typical insulation displacement connector of this kind. In this prior art arrangement the mounting of the terminal elements in the insulating clamping elements was achieved by the use of interlocking barbs and gave rise to a completely rigid structure. This complete rigidity sometimes gave rise to problems in mounting the connector in the predrilled holes of a printed circuit board. Furthermore, in arrangements such as that disclosed in Patent Specification GB 1596347, the insulated wires are only connected to the connector by two sharp wire stripping jaws. Accordingly, if the wire is accidentally jerked, it is possible for the jaws to sever the wire completely.

In one aspect the present invention may be considered to provide a conductive terminal element comprising an elongate spine having a first longitudinal slot extending along a longitudinal axis from a mouth at one end of the spine partially along the length thereof, said first longitudinal slot being adapted to receive an insulated wire, cut the insulation and provide electrical connection between the conducting core of the wire and the terminal element, a pair of jaw portions projecting from outer edge portions of the spine and inclined at an angle inwardly to provide a second longitudinal slot parallel with but spaced from the spine, said pair of jaw portions being adapted to contact but not cut the insulation of a wire and take the strain of any forces applied to the wire externally; a neck portion of reduced cross-section extending from an end of the spine; and locking means connected to the spine via the neck portion, said locking means comprising at least one projection projecting transverse to the said longitudinal axis, the neck portion being capable of permanent deformation such that the locking means can be rotated about an axis coaxial with or parallel to said longitudinal axis in order to effect a permanent change in angular orientation of the or each projection relative to the spine.

Said terminal element is preferably a metal pressing. Said terminal may suitably comprise resilient jaw portions.

Preferably said locking means comprises two opposed projections occupying a plane transverse to said longitudinal axis and forming an angle of 900 with one another, and one of said projections being co-planar with the spine. Suitably said second slot is wider than said first slot.

Said terminal may comprise a longitudinally extending contact pin adapted to provide, for the terminal element, mechanical interlock with and electrical connection to a PCB; preferably said contact pin extends from one of said projections.

In a further aspect the present invention may be considered to provide an electrical connector comprising a terminal element and an insulating housing adapted to mount said terminal element.

Said electrical connector may comprise three adjacent insulating housings which are integrally formed in a single moulding.

In a preferred embodiment said electrical connector provides means for limiting the rotation of the locking means.

Preferably the relative dimensions of the terminal element and the insulating housing are such that in both the locked and unlocked status, there is a small amount of float therebetween.

A preferred embodiment of the invention will now be described with reference to the following drawings in which: Figure 1 shows a rear view of a terminal element; Figure 2 shows a side view of the terminal element; Figure 3 shows a front view of the terminal element; Figure 4 shows a plan view of the terminal element; Figure 5 shows a schematic view of the terminal element holding an insulated wire; Figure 6 shows a view of the first face of a moulding; Figure 7 shows a view from the top of the moulding; and Figure 8 shows a view from below the moulding.

In particular Figures 1 to 4 show a terminal element, generally denoted 10, according to the present invention. The terminal element comprises an elongate planar spine 12 which has longitudinal slot 18, centrally formed therein. The slot 18 extends from a widened, generally V-shaped mouth 20, at a first end of the spine 12, to a narrower portion 22 which extends partially the length thereof. The edges 24, which define the slot 18, are sharp and are adapted to displace the insulation 28 of the wire 26 placed therein, thus forming an electrical contact between the terminal element 10 and the wire core 30, as most clearly shown in Figure 5. A strain relief clamp 32 integrally formed with the spine 12, in the form of a pair of jaws 32, provides a second longitudinal slot 34, which is parallel to, but spaced from, the first slot 18.The second slot 34 extends the entire length of the clamp 32. The edges 36 of the jaws 32, which define the second slot 34, are blunt and are adapted to contact and grip tightly insulation 28 of the wire 26 and not cut therethrough to the core 30. At the second end of the spine 12, distant from the V-shaped mouth 20, a twistable neck portion 40 of width narrower than that of the spine 12 is centrally positioned in relation to and extends longitudinally with respect to the spine 12. Locking means 39 is attached to the end of the spine 12. Said locking means 39 comprises a first projection viz. a first intermediate planar member 14 which is disposed at the end of the twistable neck portion 40, is coplanar with and extends in a direction transverse to a major axis of the spine 12 and forms, together with the twistable neck portion 40 an L-shape.With particular reference to Figure 4 the locking means 39 further comprises a second projection viz. a second intermediate planar member 15 which is disposed at the junction of the twistable neck portion 40 and the first intermediate member 14; and extends in a direction substantially perpendicular to the plane of the spine 12. At the end of the second intermediate member 15 an elongate contact pin 16 is disposed.

The major axis of the contact pin 16 extends longitudinally with respect to the spine 12 and its minor axis subtends an angle of about 450 with respect to the plane of the spine 12.

The locking means 39 is adapted to be tisted about a longitudinally extending axis which passes through the centre of the spine 12 and the centre of the twistable neck portion 40 and is denoted A-A on the drawings.

In a preferred embodiment of the invention as hereinafter described, a plurality of identical housings 60 are formed in a single moulding; the moulding being generally denoted 59. Each housing 60 is of the general form of a tube. A cross-section of the external surfaces of the moulding is generally rectangular.

Figure 6 shows a side view of a preferred moulding comprising three housing. The structure of the housing 60 will now be described with reference to a single housing.

Each housing 60 has a pair of parallel centrally positioned longitudinal slots 62 and 64 in two opposing surfaces of the moulding. The plane which contains the central axes of both slots for each housing 60 and which has its location marked on Figure 6 by the line B-B, shall hereinafter be referred to as plane B. Both slots 62 and 64 are of equal length and extend partially down the length of the housing 60. The slot 62, disposed on a first side of the housing 60 is most clearly shown in Figure 6 and has a widened top mouth portion. The other slot 64 on a second side of the housing 60 and shown in Figure 7 is of uniform thickness along its entire length. A base structure 68 is provided at the lower extremity of the housing 60.The base 68 has a shaped orifice 66 formed therein, the geometry of which is the same as the cross-section of the locking means 39, this is most clearly shown in Figure 8. A planar dividing member 69 is formed on the base 68 and lies substantially in the plane B. Said dividing member 69 upstands longitudinally from the base as far as the lower extremities of the slots 62 and 64, and projects laterally from the second side wall to the periphery of the shaped orifice 66.

In order to mount the moulding 59 to a PCB, two integrally formed mounting pins 70 and 72 are provided at diametrically opposite end portions of the moulding 59.

The mounting pin 70 projects from a locally longitudinally extended second side wall portion 71 and is in line with the said second said wall. The mounting pin 72 projects from a locally extended first said wall portion, which has been extended both laterally and longitudinally forming a protruding ridge 73 as shown in Figures 6 and 8. Since the mounting pin 72 projects from the protruding ridge 73, it is parallel to, but spaced slightly out of line with the first side wall. Both mounting pins 70 and 72 have been mounted on extended wall portions which have been longitudinally extended by the same amount. Complementary locally extended wall portions have been added to the other pair of diametrically opposite corners, however, these do not have pins mounted thereon.

In order to mount the terminal element 10 into a housing 60, the terminal element 10 is brought into sliding engagement with the top of the housing 60, in such a way that the locking means 39 is in line with the shaped orifice 66. On sliding the terminal element 10 into the housing 60, the first and second slots 18 and 34 respectively of the terminal element 10 occupy plane B of the housing. Furthermore, the dividing member 69 is located between the jaws 32. Once the terminal element is fully inserted, the locking means 39, projects beyond the base 68. In order to secure the terminal element therein, the twistable neck portion 40 is permanently deformed by rotation of the locking member 39 about its central axis thus permanently dealigning itself with the shaped orifice 66, thereby locking the terminal element 10 in the housing.

The dimensions of the terminal element 10 are such that when it has been locked in a housing 60, there is a small amount of "floating" movement between the terminal element 10 and the housing 60. This enables the connector to be used even if the holes in the PCB are slightly out of line.

Figure 5 serves to illustrate the way the strain relief mechanism operates. The line x-x indicates the direction that the wire 36 is likely to be tugged. It can be seen that the blunt jaws 32 tend to isolate the sharp jaws 24 from external applied forces experienced by the wire, thus decreasing the probability that a sharp tug of the wire 26 will cause movement of the conductor 30 at the interface of the conductor 30 and the jaws 24 thus maintaining the integrity of the electrical and mechanical connection between the jaws 24 and conductor 30.

Claims

1. A conductive terminal element comprising an elongate spine having a first longitudinal slot extending along a longitudinal axis from a mouth at one end of the spine partially along the length thereof, said first longitudinal slot being adapted to receive an insulated wire, displace4 the insulation and provide electrical connection between the conducting core of the wire and the terminal element, a pair of jaw portions projecting from outer edge portions of the spine and inclined at an angle inwardly to provide a second longitudinal slot parallel with but spaced from the spine1 said pair of jaw portions being adapted to contact but not cut the insulation of a wire and take the strain of any forces applied to the wire externally; a neck portion of reduced cross-section extending from an end of the spine; and locking means connected to the spine via the neck portion, said locking means comprising at least one projection projecting transverse to the said longitudinal axis, the neck portion being capable of permanent deformation such that the locking means can be rotated about an axis coaxial with or parallel to said longitudinal axis in order to effect a permanent change in angular orientation of the or each projection relative to the spine.

2. A terminal element as in Claim 1 wherein the te=,fiinal element is formed by metal pressing.

3. A terminal element as in Claim 1 or 2 comprising resilient jaw portions.

4. A terminal element as in Claims 1 to 3 wherein the first said longitudinal axis and the second slot, defined by the jaws, are centrally positioned.

5. A terminal element as in any preceding claim wherein the second slot is wider than the first slot.

6. A terminal element as in any preceding claim wherein said locking means comprises two opposed projections occupying a plane transversely to the said longitudinal axis and forming an angle of 900 with one another, one of the projections being coplanar with the spine.

7. A terminal element as in any preceding claim which further comprises a contact pin adapted to provide for the terminal element, mechanical interlock with and electrical contact to a PCB.

8. A terminal element as in Claim 5 wherein the contact pin extends from one of said projections in an axis parallel to or coaxial with the said longitudinal axis.

9. An electrical connector suitable for mounting on a printed circuit board comprising a conducting terminal element as in any preceding claim and an insulating housing adapted to house said terminal element.

10. An electrical connector as in Claim 9 further comprising means for limiting the rotation of the locking means, and hence the contact pin, at a predetermined position.

11. An electrical connector according to Claims 9 or 10 wherein the relative dimensions of the terminal element and the insulating housing are such that in both the locked and unlocked states there is a small amount of float therebetween.

12. An electrical connector constructed, arranged and adapted to operate substantially as hereinbefore described with reference to the accompanying drawings.