GB1587531A - Connectors - Google Patents

Description

(54) IMPROVEMENTS RELATING TO CONNECTORS (71) We, FERRANTI LIMITED, a Company registered under the Laws of Great Britain of Hollinwood in the County of Lancaster, 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: This invention relates to connectors, and particularly to connectors for passing signals to and from a body capable of unlimited rotational movement.

The problem of transferring signals to and from a rotating body has existed for a long time, and many solutions exist. All of these solutions have been concerned with a particular problem, and have not been of universal application. For example, electrical power may be transferred to or from a rotating body, such as a motor or generator, by means of brushes and sliprings but many limitations apply. The quantity of power transferred is limited by insulation and currentcarrying factors, and it is not usually possible to transfer electrical power and low-current information signals by the same means. In applications where rotation is limited to say a few revolutions, a device known as a "cable-winder" may be used. This comprises a drum or two cooperating drums onto which is wound one or more cables for carrying the necessary signals.

In this way low-power information signals and electrical power may be passed through separate cables, thus lessening interference problems. However, as already stated, such a device will only allow limited rotation.

It is an object of the invention to provide a connector for passing signals to and from a body capable of rotational movement without the use of slip rings or cable winders.

According to the present invention there is provided a connector for passing signals to and from a body comprising first and second body members arranged for relative rotation about a common axis, which includes first and second light-conducting members carried on the first body member and each comprising an array of optical fibres terminating around a closed circular path having its centre on the common axis, third and fourth light-conducting members carried on the second body and each comprising an array of optical fibres terminating around a closed circular path having its centre on the common axis, the first and third members being arranged such that at least one fibre of the first array always faces at least one fibre of the third array and the second and fourth members being arranged such that at least one fibre of the second array always faces at least one fibre of the fourth arrays a first core member of magnetic material mounted on the first body member and having an associated first winding, and a second core member of magnetic material mounted on the second body member and having an associated second winding, the first and second core members being located on the first and second body members respectively such that energisation of either the first or the second winding causes a voltage to be induced in the other winding regardless of the relative angular positions of the first and second body members.

The invention will now be described with reference to the accompanying drawings, in which: Figure 1 is a schematic diagram of a first embodiment; Figure 2 is an end view of one part of the connector of Figure 1; Figure 3 shows the assembled connector of Figures 1 and 2; Figures 4 and 5 show end view of alternative embodiments; Figure 6 illustrates another embodiment of the invention; and Figure 7 illustrates the addition of a rotating waveguide joint.

Referring now to Figures 1 and 2, a connector comprises two body members 10 and 11 arranged for relative rotation about a common axis 12 by means of bearings 13. The two body members are shown separated for clarity.

The body member 10 has a face 14 which is arranged to be adjacent to a face 15 of the other body member 11 when the connector is assembled. A single optical fibre 16 passes along the centre of the body member 10, on the axis 12, and ends slightly short of the face 14. A bundle of optical fibres 17 surrounds the central fibre 16 and projects beyond the face 14 to terminate in a circular array. The body member 10 also contains a ferrite core 18 having a hollow centre limb 19 surrounding the fibres 16 and 17, and an annular outer limb 20 jointed by ferrite material to form a pot core. A coil 21 is wound in the space between the centre and outer limbs. The ends of these limbs are formed flush with the face 14 of the body member 10.

The optical fibres 16 and 17 provide two optical channels which emerge from the body member 10 in any convenient way. As shown in Figure 1 these emerge from the sides of the body member.

The other part of the connector is very similar in construction, apart from the outer portion carrying the bearings 13. Hence a single optical fibre 22 passes along the axis 12 and projects beyond the face 15 of body member 11. A bundle of optical fibres 23 surrounds the centre fibre and ends short of the face 15 in a circular array. A pot core similar to that contained in the other body member has a centre limb 24 and annular outer limb 25 and carries a coil 26. As with the other part of the connector the optical fibres are shown as emerging from the sides of the body member 11.

When the two parts of the connector are assembled, as shown in Figure 3, the ends of the optical fibres 16 and 22 are adjacent to one another, as are the ends of the bundles of fibres 17 and 23. The two sets of fibres are offset from one another to prevent light from one set of fibres from entering the other set.

The fibres in each of the bundles 17 and 23 are arranged to be close enough to one another to ensure that light is passed from one part of the connector to the other.

In operation the two optical channels may be used for passing information in the form of modulated or digital signals. Most conveniently this may be done by using lightemitting diodes as the light source and lightsensitive devices such as photo-transistors as the receiver. Both channels may be used to convey information in the same direction, or one channel may be used in each direction.

The pot cores and their associated coils are used, most suitably, for the transmission of electrical power. The ferrite cores referred to are not very efficient at normal power frequencies, and frequencies of the order of 20 KIlt may be used, power of the order of 1Kw being conveyed between the two parts of the connector. So long as the corresponding core limbs are always kept close to one another, the rotation of one part of the connector relative to the other will not affect the transfer of electrical power.

The arrangement shown in Figure 1 is only one example of a connector. The optical fibres may be positioned differently; for example the outer bundles 17 and 23 may be located outside the annular core limbs 20 and 25 as indicated in the end view of Figure 4. The central fibres 16 and 22 may comprise a bundle of fibres rather than a single fibre. In another embodiment these also may be positioned in a circular array outside the pot cores, as illustrated in the end view of Figure 5. In this embodiment the centre core limb 19 need not be hollow, and an opaque screen 27 may be placed between the two sets of fibres.

In the embodiment shown in Figures 1 and 2, the two light-conducting members were spaced at different radii from the common axis 12. Figure 6 illustrates an embodiment in which the two sets of fibres are spaced longitudinally.

Referring to Figure 6 it will be seen that the two core members occupy the centre area of each body member. The two sets of fibres 16 and 17 carried by the body member 10 terminate on the outwardly-directed surface 28 of that member in two circumferential rings of apertures 29 and 30. In a similar manner, the two sets of fibres 22 and 23 carried by the body member 11 terminate on the inwardly-directed surface 31 of that member in two rings of apertures each of which faces a different one of the rings 29 and 30 on the body member 10.

If necessary some form of screen may be lo cated between the terminations of the two sets of fibres on each body member, carried by either one of the members.

As before, adequate optical coupling will take place between the corresponding sets of optical fibres on the two members regardless of their relative angular positions.

Yet another embodiment may have the two core members displaced radially and located between the two sets of fibres shown in Figure 6, so that the core carried by the body member 10 has its limbs extending to the surface 28, whilst the core carried by the body member 11 has its limbs extending to the surface 31. Other variations are possible.

The above embodiments describe a connector which allows for the transmission of electrical power and optically-encoded signals to be conveyed to and from a rotatable body. In the case of apparatus such as a radar equipment it may also be convenient to incorporate into such a connector a rotating waveguide joint.

Such joints are known, and may be added to the connector in the manner shown in Figure 7.

No detail of the waveguide joint is given; it is sufficient to say that this is a conventional waveguide joint with a central coaxial conductor. Only one body member is shown, and the bearings have been omitted for clarity.

Referring now to Figure 7, the body member 10 is formed around a rotating joint for a waveguide 35 having a central coaxial cable 36.

Immediately around the waveguide joint are arranged one set of optical fibres 16 which terminate in a circular array on the end face 14. These fibres emerge from the body member at a point 37. Surrounding the waveguide joint and the fibres 16 is the hollow centre limb 19 of the core member 18. The core has an annular outer limb 20 and a coil 21. A second set of optical fibres 17 is arranged to terminate in a ring outside the outer core limb 20, and to emerge from the body member at a point 38.

The other body member is constructed in a similar manner, and the connector assembled in the same way as the embodiment of Figures 1,2 and 3.

The embodiment of Figure 7 may be subject to all the modifications already described, except that the waveguide joint must always occupy the centre of the connector. In all the embodiments described further sets of optical fibres may be provided if necessary.

It will be seen that, in all the embodiments described, there are no wires connected across the rotating connector to impede its rotation.

Such a connector may, of course, be used in situations where only limited ortation is envisaged.

WHAT WE CLAIM IS: 1. A connector for passing signals to and from a body comprising first and second body members arranged for unlimited relative rotation about a common axis, which includes first and second light-conducting members carried on the first body member and each comprising an array of optical fibres terminating around a closed circular path having its centre on the common axis, third and fourth light-conducting members carried on the second body member and each comprising an array of optical fibres terminating around a closed circular path having its centre on the common axis, the first and third members being arranged such that at least one fibre of the first array always faces at least one fibre of the third array and the second and fourth members being arranged such that at least one fibre of the second array always faces at least one fibre of the fourth array, a first core member of magnetic material mounted on the first body member and having an associated first winding, and a second core member of magnetic material mounted on the second body member and having an associated second winding, the first and second core members being located on the first and second body members respectively such that energisation of either the first or the second winding causes a voltage to be induced in the other winding regardless of the relative angular positions of the first and second body members.

2. A connector as claimed in Claim 1 in which each of the body members has a surface perpendicular to the common axis, the first and second light-conducting members terminating on the surface of the first body member at different radii from the common axis.

3. A connector as claimed in Claim 2 in which the first and third light-conducting members pass through the centre of the first core member to terminate on the common axis.

4. A connector as claimed in Claim 3 in which the first and third light-conducting member each comprise a single optical fibre.

5. A connector as claimed in any one of Claims 1 to 4 in which each of the body members has a surface parallel to the common axis, the first and second light-conducting members terminating on the surface of the first body member at the same radius from the common axis.

6. A connector as claimed in any one of Claims 1 to 5 in which the first and second core members are made from a ferrite material.

7. A connector as claimed in any one of the preceding Claims which includes a rotating waveguide joint having a central conductor located on the common axis with the core mem bers and light-conducting members arranged around the waveguide.

8. A connector for passing signals to and from a body comprising first and second body members for unlimited relative rotation about a common axis, substantially as herein des cribed with reference to Figures 1,2 and 3 or any one of Figures 4 to 7 of the accompanying drawings.

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

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. limb 19 of the core member 18. The core has an annular outer limb 20 and a coil 21. A second set of optical fibres 17 is arranged to terminate in a ring outside the outer core limb 20, and to emerge from the body member at a point 38. The other body member is constructed in a similar manner, and the connector assembled in the same way as the embodiment of Figures 1,2 and 3. The embodiment of Figure 7 may be subject to all the modifications already described, except that the waveguide joint must always occupy the centre of the connector. In all the embodiments described further sets of optical fibres may be provided if necessary. It will be seen that, in all the embodiments described, there are no wires connected across the rotating connector to impede its rotation. Such a connector may, of course, be used in situations where only limited ortation is envisaged. WHAT WE CLAIM IS:

1. A connector for passing signals to and from a body comprising first and second body members arranged for unlimited relative rotation about a common axis, which includes first and second light-conducting members carried on the first body member and each comprising an array of optical fibres terminating around a closed circular path having its centre on the common axis, third and fourth light-conducting members carried on the second body member and each comprising an array of optical fibres terminating around a closed circular path having its centre on the common axis, the first and third members being arranged such that at least one fibre of the first array always faces at least one fibre of the third array and the second and fourth members being arranged such that at least one fibre of the second array always faces at least one fibre of the fourth array, a first core member of magnetic material mounted on the first body member and having an associated first winding, and a second core member of magnetic material mounted on the second body member and having an associated second winding, the first and second core members being located on the first and second body members respectively such that energisation of either the first or the second winding causes a voltage to be induced in the other winding regardless of the relative angular positions of the first and second body members.

2. A connector as claimed in Claim 1 in which each of the body members has a surface perpendicular to the common axis, the first and second light-conducting members terminating on the surface of the first body member at different radii from the common axis.

3. A connector as claimed in Claim 2 in which the first and third light-conducting members pass through the centre of the first core member to terminate on the common axis.

4. A connector as claimed in Claim 3 in which the first and third light-conducting member each comprise a single optical fibre.

5. A connector as claimed in any one of Claims 1 to 4 in which each of the body members has a surface parallel to the common axis, the first and second light-conducting members terminating on the surface of the first body member at the same radius from the common axis.

6. A connector as claimed in any one of Claims 1 to 5 in which the first and second core members are made from a ferrite material.

7. A connector as claimed in any one of the preceding Claims which includes a rotating waveguide joint having a central conductor located on the common axis with the core mem bers and light-conducting members arranged around the waveguide.

8. A connector for passing signals to and from a body comprising first and second body members for unlimited relative rotation about a common axis, substantially as herein des cribed with reference to Figures 1,2 and 3 or any one of Figures 4 to 7 of the accompanying drawings.