GB1563061A

GB1563061A - Detachable connector for optical fibres

Info

Publication number: GB1563061A
Application number: GB1008/77A
Authority: GB
Original assignee: Thomson CSF SA
Current assignee: Thales SA
Priority date: 1976-01-14
Filing date: 1977-01-11
Publication date: 1980-03-19
Also published as: DE2701436A1; CA1078148A; FR2338500B1; JPS52109950A; FR2338500A1

Description

(54) A DETACHABLE CONNECTOR FOR OPTICAL FIBRES (71) We, THOMSON-CSF, a French Body Corporate, of 173, 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: This invention relates to a device for establishing a detachable end to end optical connection between two optical fibres, or two bundles of optical fibres, provided with cylindrical terminals.

Accordingly to the invention, there is provided a detachable connector for the end to end connection on a same common axis of at least one set of two cylindrical terminals of a same predetermined diameter each said terminal surrounding the end of at least one respective optical fibre positioned on the axis thereof; said connector comprising: at least one connecting sleeve delimited by an internal cylindrical bore with a diameter at most equal to said predetermined diameter for receiving one said set of terminals and by an external surface generated by revolution about the same axis as said bore and comprising two first oppositely oriented frusto-conical bearing surfaces; said connecting sleeve being provided with a longitudinal slot extending over the whole axial length thereof from said internal cylindrical bore to said external surface of revolution; at least one set of a first and a second ring; each set of rings being associated with one set of two terminals and one sleeve; each ring being externally limited by a cylindrical surface and internally provided with a second frusto-conical bearing surface for engaging at least part of a respective one of said first frusto-conical bearing surfaces; a first external housing part having at least one. first flange for engaging one end termination of said first ring, and at least one internal cylinderical bore for receiving said first and second rings slidably therein: a second external housing part having at least one flange for engaging one end of said second ring; and fixing means for tightening said first and second external mounts and axially urging said first and second rings together. thereby causing a compression of the sleeve and a reduction of the diameter of the cylindrical bore therein; said first and second flanges having passages for said terminals.

In the accompanying drawings: Figure 1 is a section through a connector according to the invention: Figure 2 is a cross-section through the sleeve of Figure 1: Figures 3, 4 and 5 are explanatory diagrams: Figure 6 shows a variant of the connection sleeve; Figure 7 is an exploded isometric view of a connector comprising several sleeves.

Figure 1 is a view, partly in section, of a connector according to the invention. This connector is intended to join two cylindrical terminals 51 and 52 which terminate adjacent ends of lines for the transmission of radiation by optical fibres. As already known, the radiation is guided by total reflection in a single refractive fibre, (or in each fibre of a bundle of such fibres). A protective sheath 55 generally surrounds the fibre or the bundle of fibres.

Each terminal is formed by a hollow cylindrical member with a flat circular end face perpendicular to the longitudinal axis. the single fibre (or bundle of fibres) being located in the hollow centre and terminating in the central circular face of said end face. The assembly comprising the terminal. the radiation guide and its protective sheath is formed in such a way that the lateral cylindrical wall of the terminal is exactly centred in relation to the circular zone from which the luminous radiation transmitted emerges. Thus, centring of the refractive zones of two adjacent terminals is obtained when the cylindrical lateral walls of the two terminals are themselves centred. The alignment and intimate contact of the refractive zones may take place when the cylindrical lateral walls of the two terminals are coaxial with one another.

The connector for the terminal comprises a sleeve 1 made of an elastic material. The internal bore of the sleeve 1 defines an inner cylindrical surface 11 at the end of which chamfers 12 are provided to facilitate introduction of said terminals. The outer surface comprises two oppositely disposed frustoconical bearing surfaces 13 which are coaxial with the bore and which preferably both have the same apex angle, and two cylindrical surfaces 15 situated at the ends so that the lengths along the axis of the bearing surfaces 13 are limited. A cylindrical surface 14 situated between the two bearing surfaces 13 may be provided in order to limit the radial extension of the sleeve 1 during fixing.

A longitudinal slot, the sides of which are numbered 161, extends from one end of the sleeve to the other, and from the inner to the outer surface. The connector additionally comprises two rings 2, with axial symmetry of revolution, made of a more rigid material than the sleeve 1. The inner surface of each ring comprises a conical bearing surface 23 and a cylindrical zone 25 which limits the longitudinal extension of that bearing surface 23. The rings engage the sleeve, so that the bearing surfaces 13 and 23 fit onto one another. The outer surfaces 21 of the sliding rings are cylindrical. In addition, the connector comprises a first external housing part formed with a cylindrical bore which is equal in diameter to the external diameter of the rings 2 and which is delimited by the inner lateral wall 31. The sleeve 1 and the rings 2 fitted thereon are inserted into this bore. The connector further comprises a second external housing part 4 which is intended to engage over one end of the first housing part 3 and means 6 for both fixing the second part 4 to the first one 3 and for axially urging the rings 2 together. The other ends of the first and second parts 3 and 4 of the housing are formed with flanges pierced by passages 32 and 42 for the terminals 51 and 52, the flanges 33 and 43 controlling the movement of the sliding rings 2 towards one another under the compressive action of the means 6. The compression of the sleeve 1 and the adaption of its internal diameter to the predetermined diameter of the ferrules by a closing movement of the sides 161 of the longitudinal slot formed in the sleeve. and the alignment and fixing of the terminals is thereby achieved. In order to obtain effective axial clearance between the rings when the coupling is completed the edge formed by the joinder of surfaces 21 and 23 is removed to leave an empty space 24. In the case of Figure 1, the means are in the form of screwthreads 63 and 64 formed respectively on the first and second housing parts 3 and 4.

Figure 2 is a cross-section through the sleeve 1 on the line A-A of Figure 1. The cross-section of the sleeve assumes the form of an opened ring which provides for ready extension or radial compression of the sleeve.

Figures 3, 4 and 5 show the forces attributable to the compressive action of the housing on the rings, i.e. F, and on the sleeve. i.e. R. F,. F.. The force F which acts on the bearing surfaces 13 of the sleeve 1 generates two components of which one is the force R non-tangential to said bearing surface. This force R in turn decomposes into two component forces, of which one F2 acts radiallv of said sleeve whilst the other F1 acts in a direction parallel to the axis of said sleeve. Figure 3 illustrates the schematic decomposition of a force vector R' which is art of a force vector, into two force vectors F, and Figure 4 shows some force vectors R applied to the bearing surfaces 13 of the sleeve 1 through the bearing surfaces 23 of the rings. Figure 5 shows some radial force vectors 2 applied to the same bearing surfaces.

When the housing parts are tightened together. the magnitude of the forces R. F1. F, increase, applying their uniform actions to the bearing surfaces 13 of the sleeve by virtue of the symmetry and the configuration and arrangement of the sleeve. the rings and the bore.

The longitudinal slot in the elastic sleeve enables the sleeve to adapt its internal bore to the cylindrical surfaces of the terminals. The uniform action of the radial forces F. enables the terminals 51 and 52 to be centred and aligned. In addition. the choice of a small taper for the bearing surfaces 13 and 23 increases the pressure of the forces F2 acting on the elements to be maintained in relation to the pressure of the forces F,. In addition, the action of the axial forces F, enables the end faces of the terminals to be kept opposite one another and even to be moved towards one another. The various mechanical parameters of the device in particular the thread of elements 63 and 64 and the taper of bearing surfaces 13 and 23 are calculated in such a way that manual screwing of part 4 on part 3 generates forces R. Fl. F2 whose magnitudes remain far below that which would cause a permanent deformation of the constituent material of the sleeve.

Figure 6 is a plan view of a variant of the sleeve. The crenellated edges 161 of the longitudinal slot enable the forces R to be transmitted particularly effectively to the terminals without distorting the sleeve.

Figure 7 is an exploded isometric view of a detachable connector according to the invention, comprising several sleeves 1. In the case of Figure 7, the means for fixing the first housing part 3 to the second housing part 4 are in the form of clips 61 which engage lugs 62.

Fixing means such as these, formed by clip-type or bayonet-type fastenings, enable the forces applied to the sleeve to be readily limited to values which do not cause any permanent deformation of the sleeves 1. A detachable connector comprising several sleeves, of the type illustrated in Figure 7 may also use individual axial compression means for each sleeve. In particular, the external housing part, may be formed, with several internally screw threaded cylindrical passages each containing a corresponding externally screw threaded bush having a bearing surface perpendicular to its axis. The bearing surface then performs the same function as the edges 43 of the part 4 illustrated in Figures 1 and 7.

By way of example, a detachable connector produced in accordance with the invention and illustrated in Figure 1 has the following principal dimensions: maximum thickness of the sleeve 1 : 1.5 mm internal diameter of the bore of the housing port 3 : 7.2 mm length along the axis of the sleeve 1 : 15 mm length along the axis of the connector : 19 mm maximum diameter of the connector : 11 mm width of the straight longitudinal slot : ().5 mm material for the rings and external housing : brass material for the sleeve : acetal resin.

WHAT WE CLAIM IS: 1. A detachable connector for the end to end connection on a same common axis of at least one set of two cylindrical terminals of a same predetermined diameter, each said terminal surrounding the end of at least one respective optical fibre positioned on the axis thereof; said connector comprising: at least one connecting sleeve delimited by an internal cylindrical bore with a diameter at most equal to said predetermined diameter for receiving one said set of two terminals, and by an external surfaces generated bv revolution about the same axis as said bore and comprising two first oppositely oriented frusto-conical bearing surfaces; said connecting sleeve being provided with a longitudinal slot extending over the whole axial length thereof from said internal cylindrical bore to said external surface of revolution; at least one set of a first and a second ring; each set of rings being associated with one set of two terminals and one sleeve: each ring being externally limited by a cylindrical surface and internally provided with a second frusto-conical bearing surface for engaging at least part of a respective one of said first frusto-conical bearing surfaces; a first external housing part having at least one first flange for engaging one end termination of said first ring. and at least one internal cylindrical bore for receiving said first and second rings slidablv therein; a second external housing part having at least one second flange for engaging one end of said second ring: and fixing means for tightening said first and second external mounts and for axially urging said first and second rings together. thereby causing a compression of the sleeve and a reduction in the diameter of the cylindrical bore therein; said first and second flanges having passages for said terminals.

2. A detachable connector as claimed in claim 1. wherein said sleeve is made of a more elastic material than said rings and mounts.

3. A detachable connector as claimed in claim 1. wherein said external surface of revolution of the sleeve further comprises an annular cylindrical surface arranged between said two first frusto-conical bearing surfaces.

4. A detachable connector as claimed in claim 1. wherein said fixing means comprise screwthreads.

5. A detachable connector as claimed in claim 1, wherein said fixing means comprise clip systems.

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

Claims

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

longitudinal slot enable the forces R to be transmitted particularly effectively to the terminals without distorting the sleeve.

Figure 7 is an exploded isometric view of a detachable connector according to the invention, comprising several sleeves 1. In the case of Figure 7, the means for fixing the first housing part 3 to the second housing part 4 are in the form of clips 61 which engage lugs 62.

Fixing means such as these, formed by clip-type or bayonet-type fastenings, enable the forces applied to the sleeve to be readily limited to values which do not cause any permanent deformation of the sleeves 1. A detachable connector comprising several sleeves, of the type illustrated in Figure 7 may also use individual axial compression means for each sleeve. In particular, the external housing part, may be formed, with several internally screw threaded cylindrical passages each containing a corresponding externally screw threaded bush having a bearing surface perpendicular to its axis. The bearing surface then performs the same function as the edges 43 of the part 4 illustrated in Figures 1 and 7.

By way of example, a detachable connector produced in accordance with the invention and illustrated in Figure 1 has the following principal dimensions: maximum thickness of the sleeve 1 : 1.5 mm internal diameter of the bore of the housing port 3 : 7.2 mm length along the axis of the sleeve 1 : 15 mm length along the axis of the connector : 19 mm maximum diameter of the connector : 11 mm width of the straight longitudinal slot : ().5 mm material for the rings and external housing : brass material for the sleeve : acetal resin.

WHAT WE CLAIM IS: 1. A detachable connector for the end to end connection on a same common axis of at least one set of two cylindrical terminals of a same predetermined diameter, each said terminal surrounding the end of at least one respective optical fibre positioned on the axis thereof; said connector comprising: at least one connecting sleeve delimited by an internal cylindrical bore with a diameter at most equal to said predetermined diameter for receiving one said set of two terminals, and by an external surfaces generated bv revolution about the same axis as said bore and comprising two first oppositely oriented frusto-conical bearing surfaces; said connecting sleeve being provided with a longitudinal slot extending over the whole axial length thereof from said internal cylindrical bore to said external surface of revolution; at least one set of a first and a second ring; each set of rings being associated with one set of two terminals and one sleeve: each ring being externally limited by a cylindrical surface and internally provided with a second frusto-conical bearing surface for engaging at least part of a respective one of said first frusto-conical bearing surfaces; a first external housing part having at least one first flange for engaging one end termination of said first ring. and at least one internal cylindrical bore for receiving said first and second rings slidablv therein; a second external housing part having at least one second flange for engaging one end of said second ring: and fixing means for tightening said first and second external mounts and for axially urging said first and second rings together. thereby causing a compression of the sleeve and a reduction in the diameter of the cylindrical bore therein; said first and second flanges having passages for said terminals.
2. A detachable connector as claimed in claim 1. wherein said sleeve is made of a more elastic material than said rings and mounts.
3. A detachable connector as claimed in claim 1. wherein said external surface of revolution of the sleeve further comprises an annular cylindrical surface arranged between said two first frusto-conical bearing surfaces.
4. A detachable connector as claimed in claim 1. wherein said fixing means comprise screwthreads.
5. A detachable connector as claimed in claim 1, wherein said fixing means comprise clip systems.
6. A detachable connector as claimed in claim 4, wherein said fixing means comprise

bayonet systems.
7. A detachable connector substantially as hereinabove described with reference to the drawing.