GB1585407A

GB1585407A - Break-jack connection strip

Info

Publication number: GB1585407A
Application number: GB27939/77A
Authority: GB
Original assignee: Mars Actel SA
Current assignee: Nexans Interface SA
Priority date: 1977-07-04
Filing date: 1977-07-04
Publication date: 1981-03-04

Description

(54) A BREAK-JACK CONNECTION STRIP (71) We, SOCIETÉ ANONYME DITE MARS-ACTEL, a French Body Corporate of, 148;Boulevard Haussmann, 75008 Paris, France, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to a breakjack connection strip for tele-communications, and in particular for a transmission distribution frame.

Break strips are intended to break or establish electrical continuity of a line, the continuity or the break being controlled by a plug or wedge. Further the strips are connected both to a multi-conductor cable of fixed wiring and to cross connection pairs called jumpers.

In presently used strips the fixed wiring is constituted by a multi-conductor cable connected to one face of the strip and the jumpers are connected to the opposite face.

In use the conventional strips have two drawbacks in particular: - firstly miniaturisation of the equipment to which the strips are now connected, requires a strip of given size to have double the previous capacity, thus in a fixed amount of space for transmission equipment, the present capacity is 84 pairs but a draft specification by telecommunications authorities will increase this to 168 pairs in the same space.

- secondly increasing air pollution leads to corrosion which reduces the reliability of the break contacts. In order that friction should not effect the surface of the contact it is usual to employ very hard alloys, but these alloys do not stand up very well to certain corrosive agents (e.g. sulphur compounds). It has also been expected that the friction would automatically clean the contacts and improve reliability, but this expectation has often been disappointed.

The present tendency is in the opposite direction, i.e. to use soft surface materials (for example lead tin alloys) which are practically incapable of oxidation, the malleability of the contact parts ensuring as a bonus a closer contact. However such coverings deteriorate under friction and have not been used up to now for break contacts.

A strip embodying the invention comprises connection pins on its rear face, and it should be mounted in a support bracket which enables it to pivot to provide access to the said connection pins for their connection to the fixed wiring.

This has the effect, without any modification of the separation of the existing of doubling the available capacity.

In the break strips now used the continuity of the transmission line is provided by a removable continuity plug. It is thus necessary to have one plug per line to be connected.

The present invention has the aim of providing a break-jack connection strip where continuity is provided by means internal to the strip thereby avoiding the need for a removable connection plug per line to be connected. Further this new arrangement makes it very simple to provide test plugs or line transfer plugs as well as break wedges.

The present invention provides a breakjack connection strip constituted by a stack of components, wherein each component comprises mechanically rectangular plate of insulating material having relatively large upper and lower faces, surrounded by relatively narrow edges, and including connection means whereby the upper face of one plate may be connected to the lower face of another plate by engaging mating slideways of the plates and sliding in a direction substantially parallel to the faces; and wherein each component comprises electrically a set of contact springs supported so that they project outwardly from a first one of the edges to form a first set of connection pins and inwardly across the plate to press resiliently on a corresponding set of contact tracks on the plate, which tracks are electrically connected to a second set of connection pins which project outwardly from at least one other one of the edges; the edge opposite the first edge including orifices through which a plug or a wedge may be inserted to separate at least one contact spring from its corresponding track.

Preferably each contact spring has a first contact surface for contact with its corresponding track and projects beyond the first contact surface in the form of a double bend to provide a second contact surface parallel to the first and in a plane further from the track, the spring projecting beyond the second contact surface in the form of a camming surface to cooperate with a plug or wedge, during insertion thereof into the corresponding orifice to cam the spring against its resilient bias so that its first contact surface loses contact with the track while its second contact surface rests on the plug or wedge and urges it resiliently against the track.

It is also desirable to have an end stop placed to prevent a plug or wedge entering far enough to come into direct contact with the first contact surface or with that part of the track with which the first contact makes contact.

Any convenient number of these components can be stacked by sliding one into the other to form a break-jack connection strip of a desired capacity.

The characteristics of the invention will appear from the following description of an embodiment which is given by way of example with reference to the accompanying drawings in which: Figure 1 is a perspective view of a distribution frame showing two break-jack connection strips, one in the rear cabling position and the other in use; Figure 2 is a front view of a break-jack connection strip; Figure 3 is a side view of the break-jack connection strip; Figure 4 is a plan view of the break-jack connection strip; Figure 5 is a plan view of a plate; Figure 6 is a side view of the plate in cross section; Figure 7 is a plan view of the lid of a plate; Figure 8 is a detail view of the mounting of a connection pin; Figure 9 shows a contact spring in the operative position (line continuity); Figure 10 shows a contact spring in a break position (line interrupted); Figure 11 shows a contact spring with a shunt connection for a transfer; Figure 12 shows a test plug equipped with a lead; Figure 13 is a diagram of the connection of a break-jack connection strip in use before a transfer; Figure 14 is a diagram of a break-jack connection strip in use after the transfer; Figure 15 shows the transfer lead equipped with connection plugs; Figure 16 is a diagram of the connection of two break-jack connection strips during a transfer; Figure 17 shows the operation of the connection device and the transfer lead; and Figure 18 is a diagram of the connections of the strips of Figures 13 and 14 after the transfer.

Figure 1 shows a part of a distribution frame 1 with two break-jack connection strips 2 and 3 mounted thereon. The strip 2 is fixed in a reverse, or wiring position, while the strip 3 is in its operating position. The strips 2 and 3 are held in respective support brackets 4 and 5. Since the principle of pivoting the strips in their brackets and of their connection to fixed wiring are described in detail in the applicant's French patent application number 75 18 046 of the 10 June 1975 (and published under the number 2314630), this description will restrict itself to that which is essential for the understanding of the present invention.

In this invention the break-jack connection strip 6 of Figures 2 and 3 is constituted by a stack of intermediate plates 7, two end plates 8 and 9 and two end covers 10 and I 1, together with two labels 12 and 13 and a support bracket 14.

Figure 3 shows better the method by which the different plates are juxtaposed.

Each plate 7, 8 or 9 has a downwardly projecting dovetail 15 on its lower surface and an upwardly facing dove-tail receiving cavity or slideway 16 in its upper surface. It can be seen that assembly of one plate to another is performed simply by sliding the dovetail 15 of one into the cavity 16 of the other. The assembly thus constituted is locked by low ridges 17 and 18 disposed on the upper surface of each plate (see Figs 5 and 6) snapping into grooves 19 and 20 disposed on the lower surface of each plate.

Figure 4 is a plan view of a connection strip 7 seen from above, with the right hand side of the top cover cut away to show some important details.

The pegs 21 and 22 of the end plate 8 and the co-operating slots 23, 24 and 25 of the support bracket 14 can be seen as described in the above-mentioned French patent specification. The pegs 21 and 22 are directly moulded on the end plate 8 and similar pegs are to be found on the end plate 9.

The covers 10 and 11 are each pierced by two holes (not visible in the drawings) through which the pegs 21 and 22 pass to enable the connection strip 6 to pivot in the support bracket 14 by means of the slots 23, 24 and 25 therein. The covers 10 and 11 are held captive between the support bracket 14 and the end plates 8 and 9. The shape of the covers is such that the pins 26 of the rear connections and the pins 27 and 28 of the side connections are behind the outer edges of the covers and are thus protected from falling objects, especially from metallic objects which might otherwise cause short circuits across the pins.

The covers 10 and 11 also have the purpose of holding the labels 12 and 13 captive, while nonetheless retaining the possibility of their easy removal.

As can be seen on Figure 4 the labels 12 and 13 are slid into label carriers 29 and 30 and are recessed behind the cover 10. In Figure 2 it can be seen that the labels are disposed on either side of the front face of the strip and that they are supported on the lower cover 11 while the upper cover holds them captive.

To remove a label 12 for example it is sufficient to lift up the corner 31 of the cover 10 in the direction of the arrow "F" (Figure 4) thereby clearing enough space for the label to be slid out. Once this operation is over the cover returns to its original position by virtue of its flexibility.

In Figure 5 there is a plan view of an intermediate plate 7 as seen from above.

The intermediate plate 7 is made of plastics material. Each intermediate plate in this example is intended to receive 6 pairs of conductors from a multi-conductor cable constituting the fixed wiring and 6 individual pairs or jumpers constituting the cross connection wiring. The connection pins are disposed over three of the faces of the plate as has already been described.

The connection pins 26 on the rear face, receive the fixed wiring, the connection pins 27 and 28 on the two side faces are for receiving the cross connection wiring.

At the rear of the plate, on either side of the connection pins 26, there are two protective projections 32 and 33 integrally moulded with the plate and providing protection to the pins and to the conductors of the fixed wiring and for forming a continuous vertical barrier as can be seen in Figure 3.

Thus the rear connection pins 26 are protected both by the covers 10 and 11 and by the projections 32 and 33 which have the particular function of preventing an accidental catching of the jumper wires on the rear pins 26 during wiring of the jumpers onto the side pins 27 and 28.

In Figure 5 the label carriers 29 and 30 can be seen on each side of the front face of the strip such that when all the plates are stacked together the label carriers have the form shown in Figure 2.

Also in Figure 5 resilient projections 34 and 35 can be seen at the rear of each side face of the plate. These projections are integrally moulded with the plate and their ends are terminated by upwardly directed tongues 36 or 37. During assembly of a complete connection strip the combination of these projections and tongues (see Fig. 2) forms resilient passages 38 and 39 for receiving the jumper wires of the cross connection wiring.

Figure 6 shows a section through an intermediate plate 7. Inside this plate there are metallic spring blades 40 terminated at one end by the connection pins 26. There are thus as many metallic spring blades 40 inside each plate as there are connection pins 26 at its rear.

It should be noted that according to the principal of this break-jack connection strip the contact 40 is identical for all the circuits, in contrast to many such devices which use contacts that are different from each other.

This arrangement allows for a cheaper industrial manufacture. Each intermediate plate 7 is closed by a lid 41 made of an insulating material and which includes metal tracks 42, 43 and 44 which are engraved or glued (as for a printed circuit) on its inner surface, see Figure 7. The lid is kept in place by moulded lips 45 and 46.

Figure 7 shows the pattern of the tracks 42, 43 and 44 of the lid as well as the side connection pins 27 and 28 for receiving the jumper wires. The connection pins 27 and 28 are fixed to the lid 41 and are connected electrically to the tracks 42 and thus also to the tracks 43 and 44 -- see Figures 7 and 8.

Another advantageous variant not shown here of the lid part may include cut-out metal elements which are of one piece forming both the side connection pins 27 and 28 and the tracks 42, 43 and 44.

In such a solution the lid 41 would be a simple plate of insulation material. The lid 41 can also be done away with; in this case the plate is closed by the application of the following plate.

The continuity of each of the electrical circuits is based on the same principles.

With reference to Figure 6 an electric current coming from the fixed wiring enters via the connection pin 26, flows along the metal blade 40 whose active part 47 is in direct contact with the track 44 of Figure 7, then the current flows along the tracks 43 to 42 to arrive at the cross connection wiring via the side connection pin 28. Since all the blades 40 are of the same length they all apply the same contact pressure to the track 44.

In the methods of contact breaking used at present, an electrical circuit is broken by inserting a wedge between the live parts of the contacts, which requires the contacts to move through a distance equal to the thickness of the wedge which results in a large deformation of the blades and because of their large displacement, also results in a corresponding waste of space.

Further the fact of sliding a piece of insulating material between the live parts of the contacts may lead to the deposition of insulating particles which can subsequently have a degrading effect on the electrical quality of the contacts.

An advantageous feature of the breakjack contact strip resides in the use of a spring metal blade of a particular shape associated with a contact track which, while reducing the dimensions of the assembly, has the added advantage of never inserting the wedge between the contact surfaces of the contacts.

Figures 9, 10 and 11 will make it easier to follow the explanation.

In Figure 9 the device can be seen it its position of electrical continuity. The contact surface 47 of the spring metal blade 40 is in direct contact with the track 44 of the lid 41. The spring metal blade 40 terminates in two curved portions 48 and 49 leading to an inclined portion 50. The curved portion 49 is at a distance from the track 44 of the lid 41 while the end 51 of the inclined portion 50 is slightly behind the lower portion of the opening 52 provided in the front face of the plate 7.

In Figure 10 the device is shown in the break position of the electric circuit. A break wedge 53 of insulating material is introduced into the opening 52, and has a shaped end 54 which slides on the inclined portion 50 of the spring metal blade 40, passing over the curved portion 49 and coming to a stop against a vertical stop 55 moulded directly on the plate 7.

In this position it can be seen that the contact surface 47 is no longer in electrical connection with the track 44 and that this has been achieved with a reduced movement of the blade 40 and without direct intervention on the contact surface 47 by the wedge. As a result of this no foreign bodies are deposited in the contact zone of the device and the contact surface remains clean with unchanged electrical behaviour.

By way of example, supposing that the thickness of the break wedge 53 is e and e 2 is the distance between the curved portion 49 and the track 44 (in the Figure 9 position) it can be seen that the break distance BD between the contact surface 47 and the track 44 is e BD= 2 In the course of normal exploitation of a telephone line it is necessary to be able to test different parts of the circuits separately from each other, and the presence of a break-jack connection strip makes this possible.

If the wedge is provided with electrical contacts and a lead, it is possible to break the telephone circuit with the wedge and apply appropriate connections to measuring circuits either for the line side or for the jumper side.

Figure 11 shows a device in position both for breaking the circuit and for testing it. A test plug 56 is made of insulating material and includes conductor circuits stuck on its opposite faces (printed circuit). For a tele phone circuit the test plug 56 comprises two tracks on both its upper and its lower surfaces and an electric lead having four conductors. Each conductor is electrically connected to a corresponding one of the tracks of the test plug by soldering or by any other appropriate means.

Figure II will be explained with reference to a single line wire and a single jumper wire, it being well understood that the pro cess is the same for the other conductors in question.

The test plug 56 is connected to a multi conductor lead 57. A conductor 58 is elec trically connected to the track 59 on the upper part of the test plug 56, a conductor 60 is electrically connected to the track 61 on the lower part of the test plug 56. The tracks 59 and 61 run over the whole length of the test plug 56 (see Fig. 12).

A test plug is introduced into the opening 52 in the same way as a break wedge 53, the shaped end 62 sliding over the inclined portion 50 of the spring metal blade 40 passing over the curved portion 59 and coming to a stop against the vertical stop 55 of the plate 7.

In this position it should be noticed that the contact surface 47 is no longer in elec trical connection with the track 44 and that this has been achieved with a reduced dis placement of the spring metal blade 40 and without direct contact on the contact surface 47.

It should also be noted that the test plug cannot deposit impurities in the contact zone of the device which means that the contact surfaces remain clean and retain constant electrical quality.

By way of example if the test plug has the same thickness e as the break wedge (Figure 10) the same break distance will be obtained between the contact surface 47 and the track 44, e BD = 2 When the test plug 56 is placed in the device it can be seen that electrical continuity of the line is no longer ensured since the contact surface 47 is no longer in connection with the track 44. Instead the curved portion 49 is pressed against the track 61 of the test plug thus providing electrical continuity of one wire of the fixed wiring connected to the connection pin 26 to any desired test apparatus via the lead 57 whose conductor 60 is soldered to the track 61 of the test plug 56.

The pressure exerted in the direction P by the spring metal blade 40 at its curved portion 49 urges the track 59 of the test plug 56 against the track 44 of the lid 41 thereby ensuring electrical continuity of a jumper wire connected to a connection pin 28 with any appropriate test apparatus via the lead 57 whose conductor 58 is soldered to the track 59 of the test plug 56.

The exploitation of a telephone exchange can lead from time to time to the modi fication of the arrangement of subscriber lines within a distribution frame without at the same time interrupting the traffic. This operation can be performed using a "transfer" lead.

Imagine for example (see Figure 13) that a line LI arriving on a strip A and connected towards equipment El is to be replaced (see Figure 14) by a line L2 arriving on a strip B for connection to equipment E2.

During an intermediate interval (Figure 16) the line LI is taken out of service, the line L2 is connected to the strip B but the equipment E2 is not yet in service while the equipment El remains. Provisionally, a connection must be provided between the line L2 and the equipment El, this is "transfer" connection.

When the equipment E2 comes into service the provisional connection between the strips A and B is removed.

The present invention is advantageous in the solution of this problem.

Figure 15 shows a transfer lead con stituted by a two conductor cable 63 which has each end soldered to connection plugs 64 and 65 similar to the test plug 56 but including conductive tracks on only one face; 66 and 67 on the plug 64 and 68 and 69 on the plug 65. To perform the transfer according to Figure 16 the connection plug 64 should be inserted in the chosen opening of the breakjack connection strip A with the conductor tracks 66 and 67 facing upwards in the strip, while the connection plug 65 should be inserted in the chosen opening in the strip B with its conductor tracks 68 and 69 facing downwards.

The principle of electrical continuity between one break-jack connection strip to the other is explained with reference to Figure 17. For simplicity of explanation the continuity of only one of the wires of the pair will be explained, the other one being identical.

One of the wires of the fixed wiring of the line L2 is connected on the pin 26 of the plate B7. The introduction of the connection plug 65 into the plate B7 causes the electrical circuit to be broken by separating the contact surface 47 from the track 44, and at the same time establishes contact between the curved portion 49 and the track 69. One wire of the jumper wiring connected to the equipment El is connected to the side pin 28 (not shown in Figure 17) of the plate A7. The introduction of the connection plug 64 into the intermediate plate A7 causes the electrical circuit to be broken by separating the contact surface 47 from the track 44 and at the same time establishes contact between the tracks 66 of the plug and 44 of the lid 41.

The track 66 of the plug 64 is electrically connected by one of the conductors of the cable 63 to the track 69 of the plug 65, which has the effect of providing an electrical connection from the pin 26 of the plate B7 to the pin 28 of the plate A7 thereby providing the transfer connection.

When the temporary transfer period is over the connection plugs 64 and 65 are removed from their respective strips in order to disconnect the two strips from each other and to provide the definitive connection between the line L2 and the equipped E2 as shown in Figure 18.

WHAT WE CLAIM IS: 1. A break-jack connection strip constituted by a stack of components, wherein each component comprises mechanically a rectangular plate of insulating material having relatively large upper and lower faces, surrounded by relatively narrow edges, and including connection means whereby the upper face of one plate may be connected to the lower face of another plate by engaging mating slideways of the plates and sliding in a direction substantially parallel to the faces; and wherein each component comprises electrically a set of contact springs supported so that they project outwardly from a first one of the edges to form a first set of connection pins and inwardly across the plate to press

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

By way of example if the test plug has the same thickness e as the break wedge (Figure 10) the same break distance will be obtained between the contact surface 47 and the track 44, e BD = 2 When the test plug 56 is placed in the device it can be seen that electrical continuity of the line is no longer ensured since the contact surface 47 is no longer in connection with the track 44. Instead the curved portion 49 is pressed against the track 61 of the test plug thus providing electrical continuity of one wire of the fixed wiring connected to the connection pin 26 to any desired test apparatus via the lead 57 whose conductor 60 is soldered to the track 61 of the test plug 56.

The pressure exerted in the direction P by the spring metal blade 40 at its curved portion 49 urges the track 59 of the test plug

56 against the track 44 of the lid 41 thereby ensuring electrical continuity of a jumper wire connected to a connection pin 28 with any appropriate test apparatus via the lead

57 whose conductor 58 is soldered to the track 59 of the test plug 56.

The exploitation of a telephone exchange can lead from time to time to the modi fication of the arrangement of subscriber lines within a distribution frame without at the same time interrupting the traffic. This operation can be performed using a "transfer" lead.

Imagine for example (see Figure 13) that a line LI arriving on a strip A and connected towards equipment El is to be replaced (see Figure 14) by a line L2 arriving on a strip B for connection to equipment E2.

During an intermediate interval (Figure 16) the line LI is taken out of service, the line L2 is connected to the strip B but the equipment E2 is not yet in service while the equipment El remains. Provisionally, a connection must be provided between the line L2 and the equipment El, this is "transfer" connection.

When the equipment E2 comes into service the provisional connection between the strips A and B is removed.

The present invention is advantageous in the solution of this problem.

Figure 15 shows a transfer lead con stituted by a two conductor cable 63 which has each end soldered to connection plugs

64 and 65 similar to the test plug 56 but including conductive tracks on only one face; 66 and 67 on the plug 64 and 68 and 69 on the plug 65. To perform the transfer according to Figure 16 the connection plug 64 should be inserted in the chosen opening of the breakjack connection strip A with the conductor tracks 66 and 67 facing upwards in the strip, while the connection plug 65 should be inserted in the chosen opening in the strip B with its conductor tracks 68 and 69 facing downwards.

The principle of electrical continuity between one break-jack connection strip to the other is explained with reference to Figure 17. For simplicity of explanation the continuity of only one of the wires of the pair will be explained, the other one being identical.

One of the wires of the fixed wiring of the line L2 is connected on the pin 26 of the plate B7. The introduction of the connection plug 65 into the plate B7 causes the electrical circuit to be broken by separating the contact surface 47 from the track 44, and at the same time establishes contact between the curved portion 49 and the track 69. One wire of the jumper wiring connected to the equipment El is connected to the side pin 28 (not shown in Figure 17) of the plate A7. The introduction of the connection plug 64 into the intermediate plate A7 causes the electrical circuit to be broken by separating the contact surface 47 from the track 44 and at the same time establishes contact between the tracks 66 of the plug and 44 of the lid 41.

The track 66 of the plug 64 is electrically connected by one of the conductors of the cable 63 to the track 69 of the plug 65, which has the effect of providing an electrical connection from the pin 26 of the plate B7 to the pin 28 of the plate A7 thereby providing the transfer connection.

When the temporary transfer period is over the connection plugs 64 and 65 are removed from their respective strips in order to disconnect the two strips from each other and to provide the definitive connection between the line L2 and the equipped E2 as shown in Figure 18.

WHAT WE CLAIM IS: 1. A break-jack connection strip constituted by a stack of components, wherein each component comprises mechanically a rectangular plate of insulating material having relatively large upper and lower faces, surrounded by relatively narrow edges, and including connection means whereby the upper face of one plate may be connected to the lower face of another plate by engaging mating slideways of the plates and sliding in a direction substantially parallel to the faces; and wherein each component comprises electrically a set of contact springs supported so that they project outwardly from a first one of the edges to form a first set of connection pins and inwardly across the plate to press

resiliently on a corresponding set of contact tracks on the plate, which tracks are electrically connected to a second set of connection pins which project outwardly from at least one other one of the edges; the edge opposite the first edge including orifices through which a plug or a wedge may be inserted to separate at least one contact spring from its corresponding track.
2. A break-jack connection strip according to claim 1, wherein each contact spring has a first contact surface for contact with its corresponding track and projects beyond the first contact surface in the form of a double bend to provide a second contact surface parallel to the first and in a plane further from the track, the spring projecting beyond the second contact surface in the form of a camming surface to cooperate with a plug or wedge during insertion thereof into the corresponding orifice to cam the spring against its resilient bias so that its first contact surface loses contact with the track while its second contact surface rests on the plug or wedge and urges it resiliently against the track.
3. A break-jack connection strip according to claim 2 including an end stop placed to prevent a plug or wedge entering far enough to come into direct contact with the first contact surface or with that part of the track with which the first contact makes contact.
4. A break-jack connection strip according to any preceding claim, wherein the slideays are constituted by low ridges on one component engaging in grooves in the adjacent component.
5. A break-jack connection strip according to any preceding claim, wherein the break-jack connection strip includes a pivot at each end of the stack of components enabling the connection strip to occupy two substantially opposite positions when the strip is in place.
6. A break-jack connection strip according to any preceding claim and including at least one locking strip serving both as a label and to prevent the assembled components from sliding relative to each other.
7. A break-jack connection strip according to claim 6 and including a flexible cover at each end protecting the pins from falling bodies and serving as an end stop for the, or each label.
8. A break-jack connection strip substantially as herein described with reference to and as illustrated in the accompanying drawings.