OPTICAL FIBER CONNECTOR

Abstract: A connector for optically connecting first and second opti­ cal fiber contacts terminating first and second optical fibers in­ cludes a split ring comprising first and second split ring halves disposed around each of the contacts such that an enlarged in­ ternal bore of the split ring encloses a flange of the contact so as to allow limited relative longitudinal movement between the contact and the split ring. The split ring allows a nut to be dis­ posed over an end of the contact prior to assembling the split ring about the contact which allows the construction to be re­ duced in size.

Description: The present invention relates to an optical fibre connector for connecting optical fibre contacts. Numerous methods have been proposed in the prior art for terminating optical fibres to fibre contacts and interconnecting such contacts. In severe environments where relatively wide temperature ranges can be expected, such as in aerospace, geophysical or industrial applications, fibre optics has not seen extensive use because the cable and connectors are not adapted for these environments. Moreover, the fibre contacts are not designed to be led through conduits. European Patent Application no. 112072 describes an optical fibre connector which has a ferrule secured to each fibre end and a shape memory metal clamping sleeve to align and clamp the ferrules. The ferrules are disposed within the bore of the clamping sleeve which is mounted within a housing assembly. EP-A-0125525 discloses a resilient alignment sleeve for a fibre optic connector which provides preferential attachments to one of two terminal pins. The sleeve has a relatively thick section and a relatively thin section. It is retained on the terminal pin, which is completely surrounded by the thick section, due to increased frictional forces as compared to the thin sections. According to the present invention there is provided a connector for optical fibres which comprises a connector for connecting optical fibres, comprising: a receptacle having a bore extending axially through the receptacle, said receptacle having first and second opposite ends terminating said receptacle in axial extension; an optical fibre contact ferrule having a first flange extending from an outer circumferential surface thereof; characterised in that the contact is arranged to terminate an optical fibre and is provided with a second flange extending from an outer circumferential surface of the ferrule, and in that a split ring is disposed around the outer surface of the contact ferrule, the split ring comprising first and second split ring halves assembled around the contact ferrule such that an enlarged section of a bore within the split ring surrounds the first flange, the contact ferrule being moveable longitudinally relative to the split ring over a range defined by the axial extension of the enlarged section; and first means disposed around the split ring engageable with a first end of the receptacle so as to maintain the split ring in abutment against the first end of the receptacle when the first means is engaged with the first end. The optical fibre connector may include a receptacle having a step longitudinal bore therein forming first and second adjacent bore regions of different diameters separated by a shoulder, the first bore region being larger in diameter than the second bore region, a circumferentially resilient alignment sleeve disposed within a first bore region, a relaxed inside diameter of the alignment sleeve being less than an outside diameter of the contacts to be mated such that the contacts can be resiliently held and maintained in alignment within the alignment sleeve, and a captivating sleeve disposed within the first bore region adjacent the alignment sleeve, the sleeve being in frictional engagement with an inner surface of the first bore region so as to prevent longitudinal movement of the alignment sleeve. This construction minimizes relative X, Y, Z and angular misalignment between contact ferrules being mated. In addition, the connector preferably includes second means disposed around the split ring for preventing movement of the first means relative to the split ring in a rearwardly longitudinal direction, and a spring disposed around the contact adjacent to the split ring, one end of the spring abutting against an end of the split ring with an opposite end of the spring abutting against a second contact flange. Additional aspects of the invention will be described by reference to the following figures, of which: Figure 1 is a cross-sectional view of a single channel connector for connecting first and second optical fibre contacts together; and Figure 2 is an end view of a split ring utilized in the connector of Figure 1. Figure 1 illustrates a connector 1 for optically connecting first and second optical fibre contacts 11 together. The connector 1 includes an in-line receptacle 2 having a step longitudinal bore 3 and threads 4 on opposite longitudinal ends of the receptacle, the bore 3 having three discrete sized regions 5, 6, 7 separated by steps 8, 9. The bore accepts first and second mating optical fibre contact ferrules 11 in such a manner so as to urge ends 13, 14 thereof into abutment. The bore section 5 preferably has an inside diameter approximately the same as an outside diameter of the optical fibre contact ferrule 11 to minimize relative angular movement of the mating ends 13, 14 of the contacts 11. An alignment sleeve 16, preferably split along its longitudinal axis, is disposed within the middle bore region 6 so as to seat against bore step 8, the sleeve 16 preferably having a relaxed inside diameter slightly less than an outside diameter of contacts 11, the sleeve 16 also being resilient such that the sleeve compresses and grips the ends 13, 14 of the contact ferrules 11 and maintains these ends aligned and in a plane perpendicular to the plane of Figure 1. A captivating sleeve 19 is also disposed within the bore region 6 so as to set against the alignment sleeve 16, an outside diameter of the captivating sleeve being essentially equal to or slightly greater than an inside diameter of the bore region 6 so as to press fit within an keep the alignment sleeve 16 in place. The receptacle 2 having the alignment sleeve 16 and captivating sleeve 19 therein is thus suitable for receiving and accurately aligning the ends 13, 14 of the first and second second contact ferrules 11 due to the circumferential resiliency of the alignment sleeve 16. The connector 1 further includes first and second nuts 20 having threads 21 which are adapted to threadably engage with the threads 4 of the receptacle 2. A front face 25 of a split ring 22 has anti-rotation teeth 26 formed thereon which extends circumferentially outward from an outer circumferential surface of the front face 25, the teeth 26 being insertable into corresponding teeth slots 27 extending longitudinally inward from opposite ends of the receptacle 2. Since an outside diameter of the front face 25 of the split ring 22 is slightly less than an inside diameter of the opposite ends of the receptacle, when the teeth 26 and corresponding teeth slots 27 are angularly aligned, the front face 25 can slide within the ends of the receptacle with teeth 26 seating within the teeth slots thus preventing relative rotation between the split ring 22 and the receptacle 2, especially during rotation of the nut 20. Hence, during installation of the connector by threadably engaging the nut 22 with the receptacle 2 via the threads 4 and 21, the contact ferrule 11 and especially the mating ends 13, 14 thereof are not rotated. A particularly advantageous feature of the invention is the construction of the split ring 22. As illustrated in Figure 2, the split ring 22 comprises first and second ring halves 23 which together form first, second and third bore regions 28, 29 and 30, with the bore regions 29 being enlarged relative to the bore regions 28 and 30. The half rings 23 are simply assembled onto opposite half circumferential portions of the contact ferrule 11 so as to form an entire ring therearound and are held thereon by frictional forces since the spring 37 and the flange 31 are initially in contact with the split ring halves The bore region 29 encloses a first contact flange 31 of the contact ferrule 11. The front region 28 is sufficiently long such that when a step 32 at the back of the front bore region 28 contacts the flange 31, the contact spring 37 engaged with a front of the bore region 28 is maintained in compression in contact with a second contact flange 32. In addition, the contact spring 37 is sufficiently resilient such that a range of movement of the split ring 22 is sufficient to allow a front face 34 of the bore region 30 to contact the first contact flange 31. A length of the bore region 29 is less than a range of movement allowed by the spring 37 so that excessive axial loads are transferred to the split ring and thus to the connector by engagement between the flange 31 and the split ring face 34 or 32. To assemble the connector 1 so as to engage the ends 13, 14 of first and second contacts 11 which have previously been connected to first and second optical fibres in a manner as described in copending European Patent application no. 86309060.1-2205 entitled "Connector for Terminating an Optical Fibre" filed concurrently herewith and assigned to the assignee of the present invention, the disclosure of which is incorporated herein by reference, first the nut 20 is slipped over the front end 35 of the contact and slid down the cable to which it is connected a short distance. Thereafter, the split ring halves 23 are disposed around the contact ferrule 11 in a vicinity of the first contact flange 31 such that the flange 31 is disposed within the bore region 29 formed by the assembled split ring 22 and the spring 37 is compressed about the contact 11. Accordingly, the split ring is free to move in the direction of arrows 36 along a range defined by a longitudinal length of the bore region 29 while all the time keeping the spring 37 under compression. Subsequent to assembling the split ring 22 around the contact ferrule 11, nut 20 is slid forward around the split ring until a nut flange 39 bottoms on a split ring shoulder 38. Thereafter a C-ring 24 is disposed around the split ring 22 in a groove 40 thereof back of the nut thus captivating the nut in place. The contact 11 is now ready to be connected to the receptacle 2 by threading the nut onto the receptacle end. Accordingly, the front end 13 of the contact ferrule 11 is inserted into an end of the receptacle 2 and rotated such that the teeth 26 on the outer circumferential surface of the split ring seat within and engage the teeth slots 27 of the receptacle 2 and then the nut is screw threaded onto the receptacle. As previously described, angular misalignment of the mating ends 13, 14 is minimized and prevented by the size of the bore region 5, by the captivating sleeve 19, and by the alignment sleeve 16. Since the optical fibres within the contact ferrules 11 are precisely radially positioned within an aperture therein, an excellent connection between the fibres using the contact ferrules 11 and the connector is achieved.

Claims: A connector for connecting optical fibres, comprising: a receptacle (2) having a bore (6) extending axially through the receptacle, said receptacle having first and second opposite ends terminating said receptacle in axial extension; an optical fibre contact ferrule having a first flange (31) extending from an outer circumferential surface of the ferrule; characterized in that the contact ferrule is arranged to terminate an optical fibre and is provided with a second flange, (32) extending from an outer circumferential surface thereof, and in that a split ring (22) is disposed around the outer surface of the contact ferrule, the split ring (22) comprising first and second split ring halves (23) assembled around the contact ferrule such that an enlarged section of a bore (29) within the split ring (22) surrounds the first flange, the contact ferrule being moveable longitudinally relative to the split ring (22) over a range defined by the axial extension of the enlarged section (29); and first means (20) disposed around the split ring engageable with a first end of the receptacle (2) so as to maintain the split ring in abutment against the first end of the receptacle (2) when the first means is engaged with the first end. The connector of Claim 1, further comprising second means disposed around the split ring (22) for preventing movement of the first means relative to the split ring in a rearwardly longitudinal direction, and a spring (37) disposed around the contact ferrule adjacent to the split ring, one end of the spring (37) abutting against an end of the split ring with an opposite end of the spring abutting against the second flange (31). The connector of claims 1 or 2, the first means comprising a nut (20) having threads (21) which threadably engage the first end of the receptacle, the nut (20) having a shoulder (39) which abuts against a flange formed on an exterior surface of the split ring (22). The connector of claim 2, the second means preferably comprising a C-ring (24) disposed in a circumferential groove (40) formed adjacent a back end of the split ring, and further comprising means formed on contacting surfaces of the split ring and the receptacle for preventing relative rotation therebetween, the rotation prevention means preferably comprising teeth (26) and mating teeth slots (27). The connector of claim 1, further comprising a resilient alignment sleeve (16) disposed within the receptacle near a central bore region thereof, the alignment sleeve having a relaxed inside diameter smaller than an outside diameter of the contact ferrule to resiliently clamp the contact ferrule, a front end of the contact ferrule extending within the alignment sleeve and being clamped thereby, and further comprising a captivating sleeve (19) disposed within the central bore region adjacent the alignment sleeve (16), an outside diameter of the captivating sleeve (19) being approximately equal to an inside diameter of the central bore region such that the captivating sleeve (19) is frictionally retained in place and prevents longitudinal movement of the alignment sleeve (16), the central bore region preferably being stepped to form a narrower bore region adjacent to central bore region and preferably having a shoulder in contact with the alignment sleeve (16). The connector of claim 2, further comprising: a second optical fibre contact ferrule (11) having first (31) and second flanges (32) extending from an outer circumferential surface thereof, the second contact ferrule (11) adapted to terminate a second optical fibre; a second split ring (22) disposed around the outer surface of the second contact ferrule, the second split ring (22) comprising first and second split ring halves (23) assembled around the second contact ferrule such that an enlarged bore (29) within the second split ring (22) surrounds the first flange (31) of the second contact, the second contact ferrule being moveable longitudinally relative to the second split ring (22) over a range defined by a longitudinal length of the enlarged bore (29) of the second split ring; a second spring (37) disposed around the second contact ferrule adjacent to the second split ring (22), one end of the second spring (37) abutting against an end of the second split ring (22) with an opposite end of the second spring (37) abutting against the second flange (32) of the second contact ferrule; further first means (20) disposed around the second split ring (22) engageable to an opposite end of the receptacle so as to maintain the second split ring (22) in abutment against the opposite end of the receptacle when the further first means (20) is engaged with the opposite end of the receptacle (2); and further second means (24) disposed around the second split ring (22) for preventing movement of the further first means relative to the second split ring (22) in a rearwardly longitudinal direction, the first and second contact ferrules (11) being connected such that the optical fibres are optically connected.

Inventors: LEVINSON, FRANK H., MCCRAE, RICHARD J.
Applicants: RAYCHEM CORPORATION (A DELAWARE CORPORATION)
Application year: 1986
Main classification: G02B6
IPC codes: G02B6